Colon Cancer: Facts to Know

Experts have a message for those of us who are reluctant to get tested for cancer of the colon and rectum: Don't die of embarrassment. A check-up to detect colorectal cancer can find early symptomless cancers--or even precancers--when they are in highly curable stages.

Cancer of the colon and rectum (lower portions of the large intestine) may not get as much press as breast or prostate cancers, but colorectal cancer does have the dubious distinction of being the third most common cancer in the United States and the second leading cause of cancer death. Colon cancer claims the lives of about 50,000 men and women a year--that's far too many considering that almost no one need die of it. Screening methods can pick up the disease at its earliest, most curable stages.

Risk Factors For Developing Colorectal Cancer

The Colon Age. The most important risk factor for developing colorectal cancer is age. That's why the American Cancer Society's (ACS) revised guidelines recommend that men and women with no other risk factors start screening for it beginning at age 50.

Environment. The cause of colon cancer is unknown. But since the incidence of the disease is much greater in industrialized countries, environmental factors, including eating habits, may contribute its development. Many experts suspect that the U.S. has one of the highest rates of colon cancer in the world because of our appetite for fatty, low-fiber food.

Family History. People with a personal or family history of certain cancers or growths in the colon (polyps) or chronic inflammatory bowel diseases have a higher risk of developing colorectal cancer. Your doctor may recommend screening for colorectal cancer earlier or more frequently than usual if you have any of the following factors:
  • A personal or family history of colon cancer. The risk is greater if the cancer occurred in close relatives (parents, children or siblings) before the age of 55. About 10% to 15% of colon cancer cases are inherited.
  • A personal history of colon polyps or a close relative with multiple colon polyps (familial polyposis). A colon polyp is a growth on the inside wall of the colon and though most of these growths don't turn into cancer, some do if they grow. Doctors believe most colon cancers begin as polyps.
  • A history of inflammatory bowel disease, such as chronic ulcerative colitis and Crohn's disease.
  • A history of breast, ovarian, or endometrial cancer may also increase the risk of colorectal cancer.

Can Colon Cancer Be Prevented?

There are several measures that may help lower your risk of colorectal cancer:
  • Early-Detection Tests. The vast majority of deaths from colorectal cancer could be avoided if people took advantage of screening tests. Medicare now covers colorectal screenings and so do most health insurance providers. Trouble is, only about 40 percent of Americans age 50 and older are getting tested, perhaps because they aren't aware of the screening recommendations or are too embarrassed to discuss the subject with their doctors.
  • Aspirin. Americans who take aspirin regularly to keep their hearts healthy may also reduce their risk of cancer. Taking an aspirin every other day for 20 years may cut the risk of colon cancer almost in half, according to a study published in The New England Journal of Medicine. In addition, research conducted by doctors from St. Luke's-Roosevelt Hospital Center in New York City shows that a combination of aspirin and cholesterol-lowering drugs known as statins may nip cells in the earliest stages of cancer. Since aspirin can cause stomach irritation and bleeding, be sure to consult with your doctor before dosing yourself.
  • Estrogen Replacement Therapy (ERT). Women who take ERT to alleviate symptoms of menopause may have a significantly lower risk of fatal colon cancer. Researchers found that women who had used ERT had a 29% reduction in risk compared to nonusers. Among women who had been using ERT more than 10 years, there was a 55% reduction in risk. The risk of fatal rectal cancer also decreased with the number of years women had been using ERT.
  • Exercise and Weight Contol. The risk of developing colon cancer may be lower in men and women who enjoy regular physical activity and avoid obesity.
  • Smoking. Studies at the Harvard School of Public Health and Brigham and Women's Hospital in Boston have linked cigarette smoking to colon cancer. The studies also found that smoking at a young age (in your twenties) increases your lifetime risk of colorectal cancer. But remember that the longer you smoke, the greater your risk, so it's never too late to stop.
  • Eating Habits. Researchers thought that eating low-fat, high-fiber foods would help lower the chance of developing colon cancer. But two studies show that men and women with polyps (often precursors to colon cancer) who ate such a diet were no less likely to develp new polyps than those who did not.

    Though these results are disappointing, more studies are needed to show if a high-fiber diet might be effective in preventing polyps before they actually develop. Besides, health experts urge people to eat less fat-laden food and more fruits, vegetables, and whole grains to lower the risk of other diseases, including heart disease and diabetes. Good sources of fiber include whole-grain breads, cereals and pastas, beans, brown rice, and plenty of fruits and vegetables--at least five servings a day. Limit fat to 30 percent or less of daily caloric intake, with no more than 10 percent coming from saturated fats like butter and meat.

    Some research indicates that calcium, vitamin D, and folic acid may keep colon cancer at bay. Good sources of calcium include skim or low-fat milk and dairy products, broccoli, kale, and salmon and sardines with bones. Vitamin-fortified milk is a source of vitamin D and since it's a byproduct of the sun, outdoor activity on a sunny day can fulfill some vitamin D requirements. Folic acid is found in orange juice, leafy greens, fortified grains and cereals, some nuts and seeds, and dried beans. Other anti-colon cancer dietary measures include limiting sugar and alcoholic beverages.

Trouble is, only about 40 percent of Americans age 50 and older are getting tested, perhaps because they aren't aware of the screening recommendations or are too embarrassed to discuss the subject with their doctors.

How Do Doctors Screen for Colorectal Cancer?

Detection methods are so effective that suspicious tissue can be removed before it has a chance to develop into cancer. When colorectal cancer is found at an early, localized stage, the five-year survival rate is about 91%. The five-year survival rate drops to 66% when cancer has spread to surrounding tissue and to 8.5% when it has spread to distant parts of the body.

The most common screening methods are:
  • Digital rectal exam. To detect abnormalities, the doctor inserts a gloved, lubricated finger into the rectum. This exam is useful in detecting some polyps and cancers, but it's limited to only the rectum area.
  • Fecal occult blood test (FOBT) For this type of screening, patients take home a test kit and collect small samples from three consecutive bowel movements, then mail the kit to a lab for analysis. Traces of blood in the stool is a possible sign of cancer or benign polyps, which may be precursors to cancer. In the past, there was controversy concerning the usefulness of FOBT because of little evidence that it reduced the colon cancer death rate. But a study of 46,000 people at the University of Minnesota showed a 20 percent reduction in the cancer rate among those offered the test. According to researchers, colon cancer can be prevented by removing polyps detected by FOBT.

    To keep track of potential problems, the FOBT must be repeated every year. Patients who test positive should then get a colonoscopy to see if the blood comes from a polyp or cancer.

  • Sygmoidoscopy. To perform this exam, the doctor places a slender, flexible lighted tube into the rectum to look at the inside of the rectum and the lower part of the colon. If an abnormality is spotted, a colonoscopy is recommended to remove a small piece of the growth for testing and to examine the rest of the colon.
  • Colonoscopy. A colonoscope is a long, flexible, lighted tube that is inserted through the rectum to examine the entire colon. If a polyp is found, it can be removed. Patients are often sedated during the examination.
  • Barium enema with air contrast (double-contrast barium enema). An enema of barium sulfate is given through the rectum to partially fill and open the colon. When the substance is removed, the colon is then partially inflated with air to expand the colon and increase quality of the x-rays that are taken.

When Should I Be Screened?

Since colorectal cancer is one of the more treatable cancers, it's especially important to catch it early when chances of cure are greatest. The ACS now recommends that men and women aged 50 and older should follow one of the following examination schedules:
  • An annual fecal occult blood (stool blood) test, together with a flexible sigmoidoscopy and digital rectal exam every five years.
  • A total colon exam, either by colonoscopy with a digital rectal exam (DRE) every 10 years, or by double contrast barium enema with DRE every 5-10 years.
People should begin colorectal cancer screening at a younger age and/or undergo screening more frequently if they have a personal or family history of colorectal cancer or polyps; a personal history of chronic inflammatory bowel disease; hereditary colorectal cancer syndromes in their family.

Signs and Symptoms

See your doctor if you experience any of the following symptoms for more than two weeks. They could indicate a non-cancerous intestinal disorder, such as an ulcer or hemorrhoids, or they could be a sign of cancer.
  • Diarrhea or constipation
  • Rectal bleeding or blood in the stool
  • Stools that are smaller in width than usual
  • Abdominal gas and discomfort
  • Frequent gas pains
  • A feeling that the bowel never completely empties
  • Unexplained weight loss
  • Constant tiredness
  • Unexplained anemia

Treatment for Colon Cancer

When colon cancers are found at very early stages, the cancerous tissue plus some surrounding nearby tissue is surgically removed from the inner surface of the intestine.

If the cancer has invaded the wall of the colon, the cancer is removed along with surrounding colon tissue and the nearby lymph nodes. The surgeon then reconnects the remaining parts of the colon (surgical resection). If resectioning isn't possible, an opening in the patient's abdomen (called a colostomy) is made to allow wastes to pass out of the body. The colostomy may be necessary only until the colon has healed, or, if the entire rectum is removed, it may be permanent.

When cancer is in advanced stages, surgery may be done to relieve symptoms such as blockages and bleeding.

Chemotherapy (cancer-fighting drugs) is often recommended for colon cancer, especially if the cancer has spread to nearby lymph nodes. In advanced stages, chemotherapy or radiation may shrink tumors and relieve some symptoms.

Colon Cancer Survival Rates
Cancer StageDefinitionSurvival Rate
0Cancer has not penetrated bowel95 to 100%
1Cancer has penetrated, but is limited to, the bowel wall75 to 100%
2Cancer has spread to tissue outside the bowel walls50 to 75%
3Cancer has spread to local lymph nodes30 to 50%
4Cancer has spread to other organs10%

Treatment for Rectal Cancer

When rectal cancers are caught at very early stages the cancerous tissue and some surrounding normal tissue can be removed with surgical procedures that do not require cutting into the abdomen.

When more advanced cancer is found at the upper part of the rectum, after surgery the colon can be attached to the anus so that waste is eliminated in the usual way. When the cancer is found in the lower part of the rectum, a colostomy is needed after surgery.

If rectal cancer has spread to nearby organs, such as the bladder, prostate, or uterus, the rectum and affected organs are removed and a colostomy is needed after surgery.

A combination of chemotherapy and radiation therapy is recommended if the cancer has spread through the rectum and/or to lymph nodes.

Post-Treatment Monitoring for Colorectal Cancer

Patients who have been treated for colorectal cancer have regular follow-up exams and blood tests to monitor for any possible additional growths. It has been found that 80%-90% of colorectal cancer recurrences develop in the first two to three years after treatment,

In the fight against colorectal cancer, early detection is key to increased survival rates. The exams you undergo now--and any slight discomfort or embarrassment they may cause--could save your life.

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