Overview

Colon cancer happens when tumorous growths develop in the large intestine. It is the third most common type of cancer in the United States.

It is also the third most common cause of cancer-related death, and in 2017, 95,520 new diagnoses are expected to occur in the United States (U.S.). However, advances in diagnosis, screening, and treatment have led to steady improvements in survival.

Regular screenings are recommended after the age of 50 years.

Colon cancer and rectal cancer may occur together. This is called colorectal cancer. Rectal cancer originates in the rectum, which is the last several inches of the large intestine, closest to the anus.

Fast facts on colon cancer:

Here are some key points about colon cancer. More detail is in the main article.

• • Colon cancer affects the large intestine and it usually starts with polyps in the wall of the intestine.
  • Symptoms may not appear until a later stage, but if they do, gastrointestinal problems are common symptoms.
  • Treatment involves a combination of chemotherapy, radiation therapy, and surgery, possibly resulting in a colostomy.
  • A healthy lifestyle with a high-fiber, low-fat diet can help prevent colon cancer, and screening can detect it in the early stages.

What is colon cancer?

The colon, or large intestine, is where the body extracts water and salt from solid wastes. The waste then moves through the rectum and exits the body through the anus.

Colon cancer happens when out-of-control cell growth occurs in the large intestine.

Most colon cancer originates from noncancerous, or benign, tumors called adenomatous polyps that form on the inner walls of the large intestine.

Cancerous cells may spread from malignant tumors to other parts of the body through the blood and lymph systems.

These cancer cells can grow and invade healthy tissue nearby and throughout the body, in a process called metastasis. The result is a more serious, less treatable condition.

Symptoms

There are often no symptoms in the earliest stages, but symptoms may develop as the cancer advances.

They include:

• diarrheaor constipation
• changes in stool consistency
• loose and narrow stools
• rectal bleeding or blood in the stool
• abdominal pain, cramps, bloating, or gas
• pain during bowel movements
• continual urges to defecate
• weakness and fatigue
• unexplained weight loss
• irritable bowel syndrome(IBS)
• iron deficiency anemia

Colorectal cancer is one of the most common cancers in the United States. About one in 20 people will develop cancer of the colon or rectum in their lifetimes. It also is the second leading cause of cancer deaths when men and women are considered together and is the third leading cause of cancer death among women.

There are regional differences in colorectal cancer’s incidence and mortality throughout the country, with the lowest rates occurring among those living in Western states, and survival rates lowest among African Americans.

The good news is that the disease is not only highly beatable and treatable, but also highly preventable. Regular screening and removal of polyps can reduce colorectal cancer risk by up to 90 percent. But unfortunately, fear, denial and embarrassment keep many people from being screened.

When colon cancer is caught and treated in stage I, there is a 74 percent chance of survival at five years. Once the cancer is larger and has spread to the lymph nodes, however, the five-year survival rate drops to 46 percent. If the cancer has already spread to distant parts of the body such as the liver or lungs, the five-year survival rate goes down to 6 percent.

The large intestine is the last section of the digestive tract and consists of the colon and rectum. The colon is four to six feet long, and the last seven to nine inches of it is called the rectum. After food is digested in the stomach and nutrients are absorbed in the small intestine, waste from this process moves into the colon, where it solidifies and remains for one or two days until it passes out of the body.

Sometimes the body produces too much tissue, ultimately forming a tumor. These tumors can be benign (not cancerous) or malignant (cancerous). In the large intestine, these tumors are called polyps. Polyps are found in about 30 percent to 50 percent of adults. People with polyps in their colon tend to continue producing new polyps even after existing polyps are removed.

There are several types of polyps, the most common being hyperplastic polyps, adenomatous polyps, sessile serrated polyps and malignant polyps. Hyperplastic polyps are typically not precancerous. Adenomatous polyps (also called “adenomas”) and sessile serrated polyps may undergo cancerous changes, becoming adenocarcinomas. Malignant polyps are already cancerous.

Colon cancers develop from precancerous polyps that grow larger and eventually transform into cancer. It is believed to take about 10 years for a small precancerous polyp to grow into cancer. Therefore, if appropriate colorectal cancer screening is performed, most of these polyps can be removed before they turn into cancer, effectively preventing the development of colon cancer.

Besides adenocarcinomas, there are other rare types of cancers of the large intestine, including carcinoid tumors typically found in the appendix and rectum; gastrointestinalstromal tumors found in the connective tissue of the colonic or rectal wall; and lymphomas, which are malignancies of immune cells that can involve the colon, rectum and lymph nodes.

Causes and risk factors

Normally, body cells follow an orderly process of growth, division, and death. Cancer happens when cells grow and divide uncontrollably, without dying.

The exact causes are unknown, but colon cancer has several potential risk factors.

Polyps

Colon cancer usually derives from precancerous polyps that exist in the large intestine.

The most common types of polyps are:

• Adenomas: These can resemble the normal lining of the colon but look different under a microscope. They can become cancerous.
• Hyperplastic polyps: Colon cancer rarely develops from hyperplastic polyps, as they are typically benign.

Some of these polyps may grow into malignant colon cancer over time, if they are not removed during the early stages of treatment.

Genes

Uncontrolled cell growth can happen if there is genetic damage, or if changes to the DNA affect cell division. A genetic predisposition can be inherited from family members, but most colon cancers occur in people without a family history.

Some people are born with certain genetic mutations that make them statistically more likely to develop cancer later in life. Sometimes, a person will have this genetic feature, but cancer will not develop unless an environmental factor triggers it.

Traits, habits, and diet

Age is an important risk factor for colon cancer. Around 91 percent of those who receive a diagnosis are over 50 years old.

Colon cancer is more likely in people with sedentary lifestyles, those with obesity, and those who smoke tobacco.

As the colon is part of the digestive system, diet is an important factor. Diets that are low in fiber and high in fat, calories, red meat, alcohol, and processed meats have been linked to a higher risk of colon cancer.

Underlying conditions

Some conditions and treatments have been associated with an increased risk of colon cancer.

These include:

• diabetes
• acromegaly, a growth hormone disorder
• radiation treatment for other cancers
• inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease

Diagnosis

A physician will carry out a complete physical exam and ask about personal and family medical histories.

Diagnosis is usually made after colonoscopy or a barium enema x-ray.

Colonoscopy

A long, flexible tube with a camera on one end is inserted into the rectum to inspect the inside of the colon.

The patient may have to follow a special diet for 24 to 48 hours before the procedure. The colon will also require cleansing with strong laxatives, a process known as bowel prep.

If polyps are found in the colon, they are removed and sent to a pathologist for biopsy, an examination under a microscope that detects cancerous or precancerous cells.

A similar procedure, called a flexible sigmoidoscopy, examines a smaller portion of the colorectal area. This involves less preparation, and a full colonoscopy may not be needed if polyps are not found, or if they are located within a small area.

Double-contrast barium enema

This x-ray procedure uses a liquid called barium to provide clearer imaging results than a standard x-ray can give. Before a barium enema, the patient must fast for several hours.

A liquid solution containing the element barium is then injected into the colon through the rectum, followed by a brief pumping of air to smooth over barium layer for optimal results.

The x-ray of the colon and rectum is then taken. The barium will appear white on the x-ray, and tumors and polyps will appear as dark outlines.

If a biopsy suggests colon cancer, the doctor may order a chest x-ray, ultrasound, or CT scan of the lungs, liver, and abdomen to assess the spread of the cancer.

There may also be a blood test for a substance produced by some cancer cells called carcinoembryonic antigen (CEA).

Following a diagnosis, the doctor will determine the stage of the cancer based on the size and extent of the tumor, and on the spread to nearby lymph nodes and distant organs.

There are various systems for staging a cancer, but the main scale is from 0 to IV.

Stage 0: The tumor has not grown beyond the inner layer of the colon or rectum and has neither invaded deeper tissues nor spread outside of the colon.

Stage IV: The cancer has spread to distant sites and other organs throughout the body.

A cancer’s stage will determine the treatment options and inform the prognosis, or the likely course the cancer will take.

Treatment

Treatment will depend on the type and stage of the cancer, and the age, health status, and other characteristics of the patient.

There is no single treatment for any cancer, but the most common options for colon cancer are surgery, chemotherapy, and radiation therapy.

Treatments seek to remove the cancer and relieve any painful symptoms.

Surgery

Surgery to remove part or all of the colon is called a colectomy. The surgeon removes the part of the colon containing the cancer and the surrounding area.

Nearby lymph nodes are also usually removed. The healthy portion of the colon will either be reattached to the rectum or attached to a stoma depending on the extent of the colectomy.

A stoma is an opening made in the wall of the abdomen. Waste will pass into a bag, removing the need for the lower part of the colon. This is called a colostomy.

Some small, localized cancers can be removed using endoscopy.

Laparoscopic surgery, using several small incisions in the abdomen, may be an option to remove larger polyps.

Palliative surgery may relieve symptoms in cases of untreatable or advanced cancers. The aim is to relieve any blockage of the colon and manage pain, bleeding, and other symptoms.

Chemotherapy

Chemotherapy administers chemicals that interfere with the cell division process by damaging proteins or DNA in order to damage and kill cancer cells.

These treatments target any rapidly dividing cells, including healthy ones. The healthy cells can usually recover from any chemically-induced damage, but cancer cells cannot.

Chemotherapy is generally used to treat cancer that has spread because the medicines travel through the whole body. Treatment occurs in cycles, so the body has time to heal between doses.

Common side effects include:

• hair loss
• nausea
• fatigue
• vomiting

Combination therapies often mix multiple types of chemotherapy or combine chemotherapy with other treatments.

Radiation

Radiation treatment damages and kills cancer cells by focusing high-energy gamma-rays on them.

Radioactive gamma-rays are emitted from metals such as radium, or from high-energy x-rays. Radiotherapy can be used as a standalone treatment to shrink a tumor or destroy cancer cells, or alongside other cancer treatments.

Radiation treatments are not often used until a later stage. They may be employed if early stage rectal cancer has penetrated the wall of the rectum or traveled to nearby lymph nodes.

Side effects may include:

• mild skin changes resembling sunburn or suntan
• nausea
• vomiting
• diarrhea
• fatigue
• appetite and weight loss

Most side effects resolve a few weeks after completing treatment.

Prevention and outlook

If colorectal cancer is diagnosed in Stage I, there is a 92 percent chance of surviving at least another 5 years. At stage IV, the percentage is 11 percent.

For this reason, annual screening is recommended for men and women aged 50 to 75 years, especially since symptoms may not appear until the cancer has progressed.

The American Cancer Society suggest colonoscopy, for early detection of colon cancer, as it is the most accurate method. It visualizes the entire colon and allows the surgeon to remove polyps during the procedure.

Other screening tests include:

• annual fecal occult blood tests
• stool DNA testing
• flexible sigmoidoscopy every 5 years
• CT colonography every 5 years

These frequency recommendations depend on the individual’s risk of colon cancer.

Standard preventive measures include:

• maintaining a healthy weight
• exercising
• consuming plenty of fruits, vegetables, and whole grains
• decreasing saturated fat and red meat intake

The exact cause of colon cancer is unknown, but it appears to be influenced both by hereditary and environmental factors. People at an increased risk of colon cancer include those with either a personal or family history of colorectal cancer or polyps, individuals with a long-standing history of inflammatory bowel disease and people with familial colorectal cancer syndromes. Some of those at high risk may have a 100 percent chance of developing colorectal cancer.

Specific risk factors include:

• Personal History: A personal history of colorectal cancer, benign colorectal polyps which are adenomas or sessile serrated polyps, or chronic inflammatory bowel disease (e.g., ulcerative colitis and Crohn’s disease) puts you at increased risk for colorectal cancer. In fact, people who have had colorectal cancer are more likely to develop new cancers in other areas of the colon and rectum, despite previous removal of cancer.
• Heredity: If one of your parents, siblings or children has had colorectal cancer or a benign adenoma, you have a higher risk of developing colorectal cancer. If two or more close relatives have had the disease, you also have an increased risk; approximately 20 percent of all people with colorectal cancer fall into this category. Your risk is even greater if your relatives were affected before age 60 or if more than one close relative is affected.Additionally, there are two genetic conditions—familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC)—that lead to colorectal cancer in about 5 percent of patients.
  • Familial adenomatous polyposis (FAP). People who have inherited the FAP syndrome may develop hundreds to thousands of polyps in their colon and rectum at a young age, usually in their teens or early adulthood. These polyps are all adenomas. By age 40, almost all patients with FAP will develop colon cancer if they don’t have preventive surgery. Most people who have this syndrome begin annual colon examinations while in elementary school, and many choose to have their colon and rectum removed before cancer develops. FAP is rare, accounting for about 1 percent of all cases of colorectal cancer.
  • Hereditary non-polyposis colon cancer (HNPCC). Also known as Lynch Syndrome, HNPCC is a more common form of inherited colon cancer, accounting for about 3 percent to 5 percent of all colorectal cancer cases. While it is not associated with thousands of polyps, polyps are present and grow more quickly into cancer than in patients without HNPCC. Colon cancer in people with HNPCC also develops at a younger age than sporadic colon cancer, although not as young as in those with FAP.Cancers in patients with HNPCC tend to be fast growing and respond less to chemotherapy. The lifetime risk of colon cancer in people with HNPCC may be as high as 80 percent. People with HNPCC are also at an increased risk for other types of cancer, including cancer of the ovary, uterus, stomach, kidney andbladder.
  • MUTYH-associated polyposis (MAP): People with this syndrome, which is caused by mutations in the gene MUTYH, develop colon polyps that are destined to become cancerous if they are not removed. Their colonoscopyfindings may be similar to FAP with hundreds to thousands of polyps or not. People with MUTYH are also at increased risk of cancers of the small intestine, skin, ovary and bladder.

There are some additional rare genetic mutations associated with colon cancer. These include Turcot syndrome, an inherited condition in which people are at an increased risk of adenomatous polyps (and thus, colon cancer) and brain tumors, and Peutz-Jeghers syndrome, a condition that leads to freckles around the mouth and sometimes on the hands and feet, as well as large polyps in the digestive tract and an increased risk of colon and other cancers at a young age.

In addition, there are several gene mutations found in Jews of Eastern European descent (Ashkenazi Jews) that increase colon cancer risk. The most common mutation, which is called the I1307K APC mutation, is found in 6 percent of American Jews.

If you have a history of adenomas or colon cancer or suspect you have a family history of the disease, you should discuss this with your health care professional because you may need to begin screening for the disease at a relatively young age. In some cases, you may wish to undergo genetic testing.

• Age: The risk of colorectal cancer increases with age. Ninety percent of new cases of colorectal cancer in the United States are in people over 50. Clinical studies indicate that when screened for the disease, African Americans tend to be diagnosed with colorectal cancer at a younger age than Caucasians.
• Race: African Americans are more likely to get colorectal cancer than any other ethnic group. Compared to Caucasians, African Americans are about 10 percent more likely to develop colorectal cancer. Unfortunately, they also are more likely to be diagnosed in advanced stages. As a result, African Americans are more likely to die from colon cancer than Caucasians. In 2007, the rate of death from colon cancer among African Americans was 44 percent greater than that among whites.
• Diet: Eating a diet high in processed meats (hot dogs and some lunch meats) and red meats (lamb, beef or liver) may increase your risk of developing the disease. Avoiding red meat and eating a low-fat diet rich in vegetables, fruit and fiber (e.g., broccoli, whole grains and beans) may reduce your risk of developing colorectal cancer. Some studies suggest that boosting calcium intake helps prevent colon cancer. Until further studies are done, men should keep their intake below 1,500 milligrams because of the increased risk of prostate cancer associated with high levels of calcium. Some research has also shown that vitamin D, which you can get from foods, sun exposure or a pill, can help lower colon cancer risk, but because of the increased risk of skin cancer with sun exposure, most health care professionals don’t advocate getting more sun to reduce colorectal cancer at this time. Other studies suggest that taking a multivitamin that contains folic acid may lower colon cancer risk, but more study is needed in this area. There is some research suggesting that a diet high in magnesium may decrease colon cancer risk, especially in women. More research is necessary to find out if this link exists.
• Lifestyle: Regular exercise is a key weapon in the fight against colorectal cancer. Another significant risk factor in colorectal cancer is smoking. Get help quitting if you can’t do it on your own. And keep your alcohol intake to one drink a day or less (two drinks a day or less for men).
• Obesity: Obesity is an epidemic in the United States and has been associated with many types of cancers, including colorectal cancer. There is a strong link between higher BMI (body mass index) and waist circumference and colon cancer risk in men and a weaker association seen in women. High levels of insulin and insulin-like growth factor may play a role in development of colon cancer in obese people. Weight loss has been shown to reduce the risk of colon cancer.

Screening Tests

The American Cancer Society recommends all women and men over the age of 50 who are at average risk of colorectal cancer undergo one of the following:

• A fecal occult blood test once a year. This test detects microscopic amounts of blood in the stool and only detects tumors that are bleeding. This must be performed on three separate bowel movements, and you should avoid nonsteroidal anti-inflammatory medications (NSAIDS) for seven days and vitamin C and red meat for three days before collecting the stool samples. Your health care professional provides the necessary materials to collect the stool specimens for simple testing at home or in the office. The stool should be collected before it is in the toilet water. A wooden stick is used to smear a small sample of stool onto the slots in the test card. You will get three test cards, which, when completed, you return to your health care professional. Your health care professional may recommend this test earlier than age 50 or more frequently if you are at high risk for colon cancer and/or polyps.
• A flexible sigmoidoscopy every five years. This examination allows the health care professional to inspect the rectum and lining of the left colon with a thin tube with a light and camera on the end. To prepare for the test, you may be asked to follow a special diet (such as drinking only clear liquids) for a day before the exam and to use enemas or laxatives to clean out your colon. The sigmoidoscope is inserted into the rectum while you lie on your left side. Sedative medication is not usually given for this procedure. This test is both diagnostic and therapeutic. However, it can only detect polyps or cancer accurately in the last two feet of the large intestine. Unfortunately, the sigmoidoscopy visualizes less than half the colon and misses about half of cancers and polyps that are close to becoming cancer in the first two to three feet of the colon.
• Fecal Immunochemical Test (FIT) every year. Similar to FOBT, FIT is a stool test that also detects hidden blood (occult) in the stool and must be performed every year. However, it tests for hidden blood in a different way than FOBT and has fewerfalse positive results. Some forms of FIT only require two stool specimens versus three for the FOBT, and neither vitamins nor foods will affect FIT results (these things can affect results of a FOBT); therefore, no dietary restrictions are necessary prior to collecting the stool samples. You perform the test in a similar manner as the FOBT. Similar to FOBT, the FIT test will not detect a tumor that is not bleeding, so a colonoscopy may be necessary for further screening or if cancer is suspected.
• Stool DNA at an uncertain frequency (manufacturer recommends every five years). A new screening approach, this test is available but not yet certified by the FDA. This test detects abnormal DNA shed by tumor cells into the stool and requires an entire stool sample. Studies are under way to determine how often the test should be done and how to increase its accuracy.
• A double contrast barium enema every five years. This test involves injecting barium (a liquid imaging agent that shows up during an X-ray) through the rectum into the colon, then taking X-rays of the colon. A health care professional injects the thick, chalky liquid through a small tube inserted into your anus. You may feel an urge to move your bowels, but should hold on while the X-rays are taken. After the X-rays finish, you can expel the liquid. To avoid becoming constipated afterward, you should drink plenty of fluids to flush the barium from your system. While the procedure can be uncomfortable, it is not usually painful. This test is only a diagnostic test. If abnormalities show up, a colonoscopy must be performed. The barium enema is not a very sensitive test and misses half of polyps that are larger than 1 centimeter.
• A colonoscopy every 10 years. Similar to the flexible sigmoidoscope, the colonoscope is a longer thin black tube that allows the health care professional to examine the entire large intestine. Preparation for the procedure requires drinking alaxative the day before the colonoscopy. Adequate preparation is critically important to enable the physician to visualize the entire lining of the colon. Leftover stool obscures the view of that portion of the colon and could lead to missing lesions. The ACS recommends getting a colonoscopy starting at age 50 for the average-risk person or if a FOBT or FIT shows blood in the stool. You typically receive a mild sedative during the procedure, so you should experience minimal discomfort. The procedure itself typically lasts 20 to 30 minutes.This test is both diagnostic and therapeutic. It detects polyps and cancers found anywhere in the colon. Any polyps or other growths found during this examination are usually removed and sent to a laboratory for examination. Medicare now covers this procedure every 10 years for people over 50 who are considered average risk for developing colon cancer and every two years for people at high risk. Women and men over 50 should have a colonoscopy at least every 10 years. The American College of Gastroenterology recommends that African Americans, who tend to develop the disease at a younger age than other races, begin getting screening colonoscopies at age 45.
• CT colonography (virtual colonoscopy) every five years. This is a relatively new technique that uses a CT scan to create a three-dimensional image to evaluate the colon. It does not allow for a biopsy (tissue sampling) or polyp removal if any abnormalities are found. You must take a laxative the day before this test, similar to a colonoscopy, and if any abnormalities are found, you must undergo a colonoscopy. Most insurance companies do not cover virtual colonography as screening for colorectal cancer.

Most women find sigmoidoscopies and colonoscopies much more tolerable than they expect. Worrying about the process and undergoing the necessary preparation beforehand are often more unpleasant than the exam itself. Of the above-mentioned tests, colonoscopy is the preferred screening/prevention test, and FIT is the preferred test for patients who decline invasive cancer prevention tests.

Other tests that your health care provider might perform include:

• Digital rectal examination (DRE). Your health care professional inserts a gloved finger into the rectum to feel for any abnormalities. This simple test, which may be uncomfortable but usually is not painful, can detect many rectal cancers. However, even the longest of fingers are far too short to examine the full length of the large intestine. For this reason, other tests and examinations, such as the FOBT, flexible sigmoidoscopy and colonoscopy must be used. The rectal exam is not sufficient to screen for colon cancer.
• Genetic testing. The few hereditary cancer syndromes mentioned here are rare but are associated with mutations in specific genes. These mutations can be passed on to other family members. Thus, if your family is affected or may be affected by one of these syndromes, you may need to undergo genetic testing. If genetic testing and counseling are done properly, lives can be changed dramatically, both in terms of preventing colon cancer and lessening the psychological impact of knowing you are predisposed to the disease.Genetic testing for colon cancer raises many scientific and ethical issues. Although tests are available to identify the mutations that may predispose you to colon cancer, they are not absolutely positive predictors. Additionally, some health care professionals are not yet fully educated about the tests and may misinterpret the results.Thus, if you have a strong family history of colon cancer, you should be seen at agenetic screening center. Talk to your health care professional about the genetic screening process and how to locate such a center.

If there is a reason to suspect that you have colorectal cancer, your health care professional will take a complete medical history and perform a physical examination as part of an initial evaluation.

Symptoms

Symptoms of colorectal cancer include:

• Change in bowel habits (diarrhea, constipation or narrow stools for more than a few days)
• Urgency for a bowel movement or feeling like you need to move your bowels even if you just did
• Blood in the stool
• Stomach pain
• Weakness and/or fatigue

Contact your health care professional if you experience one or more of these symptoms.

Diagnosis

Because the symptoms of colon cancer are vague and typically occur late in the development of the cancer, a variety of tests are used to both screen and diagnose the disease. Screening tests look for disease in those who look and feel healthy, ideally catching the disease as early as possible or, in the case of colon cancer, even before the precancerous lesion has turned into cancer. Diagnostic tests look for the cause and determine the extent of the disease in someone who has obvious symptoms.

A bowel preparation is often required before many of these tests, especially a colonoscopy. This involves cleaning out your bowel the night before the test with a laxative solution. It is important that the bowel be clean so the physician performing the colonoscopy gets the best look at your colon. Since some preparations can affect your blood level for certain electrolytes, your health care professional will tell you which preparation to use for your procedure.

Diagnostic Tests

• Flexible sigmoidoscopy or colonoscopy. Sigmoidoscopy is a procedure that allows a physician to view the lining of the rectum and the lower part of the colon. This area accounts for less than one-half the total area of the rectum and colon. If a mass or any other types of abnormalities are seen through the flexible sigmoidoscope or colonoscope, a sample (biopsy) is taken for further examination by a pathologist to determine if it is cancerous or benign.
• Complete blood count (CBC) and blood chemistry. The CBC determines whether you are anemic because many people with colorectal cancer become anemic due to prolonged bleeding from the tumor.
• Computed tomography (CT). In this test, a rotating X-ray beam creates a series of pictures of the body from many angles, helping visualize any masses that may indicate that the colon cancer has spread to your liver or other organs.
• Magnetic resonance imaging (MRI): Like CT, magnetic resonance imaging displays a cross-section of the body. However, MRI uses powerful magnetic fields and radio waves instead of radiation.
• Chest x-ray. This familiar imaging test detects if colorectal cancer has spread to the lungs.
• PET scanning: This test can determine if certain cells are using glucose more than other cells. Cancer cells, which are actively dividing, use more glucose so they light up on a PET scan. This test is used to follow cancer and can be combined with a CT scan to better localize a possible recurrence. It is important to remember that not all tumors will be responsive to PET/CT imaging.

Colorectal Cancer Stages

As with all cancers, there are various stages of colon cancer:

• Stage 0: Abnormal (dysplastic) cells have been found in the innermost lining (mucosa) of the colon. This stage is also known as carcinoma in situ or intramucosal carcinoma, and there is a very small chance these cells have spread, so this stage is not considered to be invasive cancer.
• Stage I: Cancer has spread to the inside lining of the colon but hasn’t spread beyond the colon wall or rectum.
• Stage II: Cancer has spread through the colon or rectum and may invade surrounding tissue, but no lymph nodes are involved.
• Stage III: Cancer has spread to the lymph nodes, but not to distant sites.
• Stage IV: Cancer has spread to other distant parts of the body, such as the liver or the lung.

Treatment

Surgery is often required to treat colorectal cancer. The surgical procedure used depends on where the cancer is located. Most patients who undergo surgery for colon cancer have an open abdominal operation, where the surgeon makes an incision in the abdomen and removes the tumor and any affected lymph nodes. In some cases, however, a procedure called laparoscopic colon cancer resection may be used. Like open abdominal surgery, laparoscopic surgery is performed under general anesthesia, but multiple, much smaller incisions are made, which leads to a shorter recovery time. Studies have shown similar results when open abdominal and laparoscopic techniques are used to remove colon cancer. A surgeon experienced at laparoscopic surgery should perform these surgeries.

Occasionally, early cancerous changes may be limited to a portion of an otherwise noncancerous polyp. In these cases, it is sometimes possible to remove some very early colon cancers during a colonoscopy.

If part of the colon needs to be removed due to a larger cancerous tumor, the surgeon will remove the affected portion and leave as much of the healthy colon behind as possible. In rectal cancer, the rectum is removed.

In many cases, the surgeon will be able to reconnect the healthy portions of the colon and rectum, which allows waste to flow through the colon to the rectum. If this is not possible, you may need to have a colostomy. A colostomy (stoma) involves creating a hole in the wall of abdomen to which an end of your colon is attached so you can eliminate waste into a special bag. Depending on the situation, a colostomy may be temporary or permanent.

You may be referred to an enterostomal therapist (a health care professional, often a nurse, trained to help people with their colostomies) as part of your initial workup. The enterostomal therapist can address concerns about how a colostomy might affect your daily activities.

Even after colon cancer has been completely removed with surgery, cancer cells can remain in the body and cause relapse. To kill these cells and decrease the chances of a relapse, health care professionals use chemotherapy. Not all people need chemotherapy after surgery. Those most likely to receive chemotherapy are people at risk for recurrence, namely, those with stage III colon cancer or high risk stage II.

For some rectal cancers, chemotherapy is given along with radiation therapy in an attempt to shrink the tumor before surgery. This is called neoadjuvant chemotherapy.

Several chemotherapy drugs are used to treat colon cancer. In many cases, two or more of these drugs are combined for more effective treatment:

• 5-Fluorouracil (5-FU): 5-FU is part of most chemotherapy treatments for colorectal cancer, and it is often given together with another chemotherapy drug called leucovorin (folinic acid). 5-FU may be given through a vein over two hours or as a quick injection followed by continuous infusion via a battery-operated pump over the following one or two days. In most cases, patients get 5-FU every two weeks for six months to a year. Side effects include nausea, loss of appetite, diarrhea, low blood cell counts and sensitivity to sunlight.
• Capecitabine (Xeloda): A chemotherapy drug in pill form, Xeloda changes to 5-FU once it reaches the tumor and is about as effective as continuous intravenous 5-FU. Patients taking capecitabine usually get it twice a day for two weeks, followed by a week off. Capecitabine is a convenient option to 5-FU because it can be taken at home, but it still has similar side effects.
• Irinotecan (Camptosar): This drug is often combined with 5-FU and leucovorin in a regimen called FOLFIRI. Irinotecan may also be used by itself as a second-line therapy if other chemotherapy drugs are not effective. It is given intravenously over 30 minutes to two hours. Some people cannot break down irinotecan, which leads to severe side effects like diarrhea and low blood counts. This inability to break down the drug is due to an inherited gene variation that can be tested for, so it is possible to predict how you will react. If you are taking irinotecan and experience severe side effects, call your doctor right away.
• Oxaliplatin (Eloxatin): For the treatment of advanced colorectal cancer, oxaliplatin is usually given together with 5-FU and leucovorin (known as the FOLFOX regimen) or with capecitabine (known as the CapeOX regimen) as a first- or second-line treatment. It may also be used as adjuvant therapy after surgery for colorectal cancers at earlier stages. Patients take oxaliplatin intravenously over two hours, usually once every two or three weeks. Oxaliplatin may affect peripheral nerves, leading to numbness, tingling and heightened sensitivity to temperature, especially in the hands and feet. In most cases, these side effects go away once patients stop taking the medication, but they can persist. Talk to your doctor about potential side effects before you start taking oxaliplatin.

Individuals with advanced colon cancer may receive targeted drugs that help stop cancerous tumors from growing. These drugs include bevacizumab (Avastin), cetuximab (Erbitux) and panitumumab (Vectibix). They may be given alone or together with chemotherapy.

Not all people benefit from targeted medications. Researchers are currently examining who are most likely to respond. Until then, health care professionals will continue to weigh the risks and benefits of targeted drugs before they prescribe them for people with advanced disease.

Radiation therapy may benefit some people with rectal cancer, but it is not usually used in the treatment of early stage colon cancer. Like chemotherapy, radiation may be helpful for patients who are at high risk of cancer recurrence, for instance if the cancer has spread to nearby organs. In general, the goal of radiation is to reduce chances of colon cancer recurrence rather than to improve survival.

For those whose colorectal cancer has metastasized to a few areas in the liver, lungs or elsewhere in the abdomen, surgically removing or destroying these metastases can increase survival.

If the cancer comes back in only one part of the body, you may need surgery again. If it has spread to several parts of the body, you may receive chemotherapy and/or radiation therapy.

Prevention

The most important line of defense against colorectal cancer is screening for colorectal cancer. You should follow the established guidelines for screening procedures so that any precancerous polyps can be removed before they turn into cancer and, if cancer exists, it can be detected at the earliest possible stage. If you are at average risk of colorectal cancer, the American Cancer Society recommends that all women and men over the age of 50 undergo one of the following:

• annual fecal occult blood test
• flexible sigmoidoscopy every five years
• double contrast barium enema every five years
• colonoscopy every 10 years unless you are African American, in which case your screening can begin at age 45
• virtual colonoscopy (CT colonography) every five years
• stool DNA testing, interval uncertain (a new screening approach, this test is available but not yet certified by the FDA)

Any positive screening test should be followed by an appropriate and complete diagnostic evaluation of the colon including a colonoscopy with biopsies, if necessary.

If you are at an increased risk of colorectal cancer or adenomas because of a family history of cancer or polyps, you should follow the above recommendations and also:

• Begin colorectal screening at age 40, or 10 years before the youngest case of colon cancer in the immediate family.
• Discuss genetic counseling and/or testing with your health care professional.

If you are at an increased risk for colorectal cancer for a reason other than family history, such as a personal history of inflammatory bowel disease, you may also need to begin screening before age 50. Screening recommendations vary based on your particular risk factors; discuss your individual screening schedule with your health care professional.

Modifying your diet and exercise may help decrease your risk of forming colon polyps and/or colon cancer. A diet rich in vegetables, fruit and fiber and low in fat may reduce the risk of developing colon cancer. Some suggest that increasing intakes of calcium and vitamin D can help prevent colon cancer. (Men should keep their intake below 1,500 milligrams because of the increased risk of prostate cancer associated with high levels of calcium.) Calcium can be found in dairy products, calcium-fortified products such as orange juice, soy and dark green vegetables. Other research has shown that taking a multivitamin containing folic acid (a B complex vitamin) decreases the risk of colon cancer, but more study is needed. There is some research suggesting that a diet high in magnesium may decrease colon cancer risk, especially in women. More research is necessary to find out if this link exists.

Regular exercise is important in preventing colon cancer. Experts say that vigorous exercise is not necessary. Instead, just incorporate more activity into your daily routine, such as taking the steps instead of the elevator or parking your car farther from the building you are entering. Overall, the American Cancer Society recommends 30 minutes of physical activity at least five days per week and says that 45 minutes or more of moderate to vigorous activity five or more days a week may further reduce the risk of colon, breast, uterine and prostate cancers.

It is also advisable to drink alcohol only in moderation (no more than one alcoholic beverage per day for women, for a total of less than seven drinks per week, and no more than two alcoholic beverages for men, for a total of less than 14 drinks per week) and abstain from tobacco use.

Results from multiple studies show that people who regularly take aspirin and other non-steroidal anti-inflammatory medications (NSAIDS) have a lower risk of colorectal cancer and adenomatous polyps. An August 2009 study published in the Journal of the American Medical Association found that aspirin can help prevent colorectal cancer deaths as well. The study looked at 1,279 men and women with colon cancer and found that those who took aspirin regularly after their diagnoses were 30 percent less likely to die from the disease than people who didn’t take aspirin. However, the risk of stomach ulcers and other side effects associated with aspirin and NSAIDS may outweigh the benefits. Therefore, experts do not recommend people at average risk of colorectal cancer take NSAIDS as a prevention strategy. Discuss the potential risks and benefits of taking NSAIDS with your health care professional.

Facts to Know

1. The American Cancer Society estimates that about 103,170 new cases of colon cancer and 40,290 new cases of rectal cancer will be diagnosed in 2012. Combined, these cancers are predicted to cause about 51,690 deaths during 2012.
2. While colorectal cancer is the second leading cause of cancer deaths when men and women are considered together and is the third leading cause of cancer death among women, incidence among Caucasians in the United States has been decreasing, perhaps due to improved screening methods. Among African Americans, however, incidence rates have remained relatively stable.
3. The risk of developing colorectal cancer is highest among those with a family history of colorectal cancer or adenomatous polyps and those who have inflammatory bowel disease.
4. Except for those with hereditary conditions that may predispose them to developing colorectal cancer relatively early in life, 90 percent of all cases occur after the age of 50.
5. Tumors that grow in the large intestine are called polyps. A biopsy determines if the polyp is benign (not cancerous) or malignant. Benign polyps can be precancerous (adenomatous and sessile serrated) or not precancerous (hyperplastic). Thirty percent to 50 percent of the population has polyps. Over the course of about 10 years, adenomatous polyps can become cancerous if they are not removed.
6. Undergoing appropriate screening for colorectal cancer can decrease death rates from this cancer by up to 90 percent. Colorectal cancer screening is designed to detect and remove precancerous polyps (adenomas and sessile serrated polyps) before they turn into cancer and to diagnose cancer at the earliest stages.
7. If you or a close relative were diagnosed with colon cancer at age 45, then other members of your family should begin screening around age 35. If you have a close relative with colorectal cancer, you should begin screening at the age of 40 or 10 years before the age at which the youngest relative was diagnosed with cancer.
8. Cancer specialists are using more aggressive strategies to make sure cancer does not return after surgery. You may receive both chemotherapy and radiation therapy to increase your chances of a complete cure. These treatments destroy microscopic accumulations of cancer cells that cannot be seen or removed during surgery.
9. When colon cancer is caught and treated in stage I, there is a 74 percent chance of survival at five years. Once the cancer is larger and has spread to lymph nodes, the five-year survival rate drops to 46 percent. If the cancer has already spread to distant parts of the body such as the liver or lungs, the five-year survival rate goes down to 6 percent.
10. You may be able to reduce your risk for colorectal cancer by eating a diet high in fiber and low in fat, getting plenty of exercise, limiting your alcohol intake to one drink or less a day, losing weight if you are obese, taking calcium and having regular colorectal cancer screenings.

Key Q&A

1. My health care professional told me I have polyps. What are these and how will they be treated?Colorectal polyps are excess growths of tissue in the lining of your colon or rectum. They can be noncancerous (hyperplastic), precancerous (adenomas or sessile serrated polyps) or malignant (cancerous). All colorectal cancers develop from precancerous polyps. Therefore, if these precancerous polyps are removed during colonoscopy or sigmoidoscopy, they will no longer be able to grow into cancer. Most colorectal polyps are easily removed during colonoscopy without the need for surgery. Once you have polyps, you are at increased risk for developing more polyps in the future and need repeated screening to detect and remove them.
2. My father and grandmother both had colon cancer. What are my risks and what should I do?First, realize the disease is highly curable when diagnosed early. When the cancer spreads to other distant places like the lung or liver, however, the survival rate is less than 10 percent. A family history of colon cancer or adenomatous polyps significantly increases your chances of developing the disease, and the more family members you have with colon cancer, the higher your risk. Make an appointment with your health care professional now to discuss your personal and family health history and to determine the next steps you should take. You will need to have colorectal cancer screening starting at the age of 40 or 10 years before the age at which the youngest relative was diagnosed with cancer. You will probably have regular surveillance of your colon by colonoscopy.
3. Is there any way to reduce my risks for colon cancer?Most important is to ask your health care professional about colorectal cancer screening beginning at age 50 (45 for African Americans) if you are at average risk or earlier if you have family members (such as your father, mother, sister or brother) who had colorectal polyps or cancer. If you undergo appropriate screening for colorectal cancer, you may decrease your risk of death from colorectal cancer by 90 percent. This is because physicians can detect and remove precancerous polyps before they turn into cancer, most effectively by colonoscopy. Research increasingly suggests that a diet high in fiber, fruits and vegetables and low in fat may help reduce your risk for colon cancer. Losing weight if you are obese may decrease your risk of colorectal cancer. Taking calcium and vitamin D may prevent formation of precancerous polyps and colon cancer. And getting regular exercise may help, too.
4. My health care professional told me my cancer had metastasized and that I had a “met” in another place besides the colon. What does that mean?“Met” is short for metastasis, which means the cancer has spread to other parts of the body. Any time your health care professional uses a word you don’t understand, stop him or her right there and ask what that word means.
5. What are my chances of a cure?No one really knows if cancer is totally cured. But it is sometimes pushed back so far it never grows again, which is called achieving remission or long-term survival. Your chances of surviving for a long time largely depend on the stage of your cancer at the time of diagnosis and the success of treatments you receive. The earlier the cancer is detected, the higher your chances for long-term survival.
6. My cancer is pretty advanced. How long have I got?Any number that a health care professional gives you is based on estimates derived from experiences with other patients. No one can tell you what your specific chances are. Survival averages are just that: averages.
7. What can I do about this ongoing pain?One of the worst things that cancer patients do is to suffer pain when they do not have to! Discuss your pain with your health care professional so that you can get the relief you need. It might be necessary to see a pain specialist. Most health care professionals can refer you to someone who specifically handles chronic pain problems. If you have severe pain, narcotics may be the best type of medicine.
8. What caused this? Was it something I did? How long did it take to grow?No one is really sure what causes colorectal cancer. It’s very unlikely that it was something you did. The tendency to get the disease may be hereditary, that is, it may run in families. A polyp in your colon can take as many as 10 years to become cancerous. Colorectal cancer is difficult to find without regular screening and often does not cause symptoms until it’s already well developed. So don’t beat yourself up that you didn’t “catch” it a few months ago.

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