Causes

No one knows for sure what causes colon cancer, but we do know some of the risk factors. Your chances of developing colon cancer are higher if you have any of the following:

• A personal history of ulcerative colitis, precancerous changes in the lining of the colon, or Crohn’s disease
• A personal history of large polyps (growths in the colon)
• A first-degree relative—mother, father, sister, or brother—who had colon cancer before 65 years of age
• Two first-degree relatives who had colon cancer at any age
• A personal history of breast, ovarian, or endometrial cancer

Age also plays a role. Most cases occur in people over 65 years of age. Fewer than 2 percent of cases occur in those individuals under 40 years of age.

Symptoms

You may not know you have colorectal cancer because there are no warning signs in the early stages of the disease. If you have a change in your bowel habits, such as bloody or black stools, your doctor will recommend that your colon be examined. The best way to know if you have colorectal cancer—before you have symptoms—is to be screened for the disease.

Know the Signs of Cancer

Cancer is a group of diseases that may cause virtually any sign or symptom. In most cases a patient’s signs and symptoms do not provide enough clues to determine the cause of illness. However, you should not overlook a symptom if it occurs, particularly if it has been going on for a time. Here are some of the general signs and symptoms of cancer:

• Unexplained weight loss
• Fever
• Fatigue
• Pain
• Changes in the skin

In addition to these general symptoms, the American Cancer Society has published the following seven common symptoms that could lead to a diagnosis of cancer:

• A change in bowel habits or bladder function. These symptoms may be signs of colon, bladder, or prostate cancer.
• Sores that do not heal. Skin cancers may bleed and resemble sores that do not heal. A persistent sore in the mouth could mean oral cancer.
• Unusual bleeding or discharge. Blood in sputum is a sign of lung cancer. Blood in the stool could be a sign of colon or rectal cancer. Vaginal bleeding could indicate cancer of the uterus or cervix. Blood in the urine is a sign of possible bladder or kidney cancer. A bloody discharge from the nipple can mean breast cancer.
• Thickening or lump in the breast or other parts of the body. Cancers of the breast, testicle, lymph nodes, and soft tissues may be felt through the skin.
• Indigestion or difficulty swallowing. These symptoms may be pointing to a cancer in the esophagus, stomach, or throat.
• Recent change in a wart or mole. An increase in size, color, or shape may indicate skin cancer.
• Nagging cough. A cough that does not go away may be a sign of lung cancer.
• Hoarseness. Hoarseness can indicate cancer of the larynx or thyroid.

Screening for Colon Cancer

Many people would rather avoid the screening tests used for colon cancer because they are embarrassed or concerned about discomfort. Don’t let these worries stop you from getting the screening you need. Early detection can save lives. Discuss the following screening options with your doctor to decide the best method for you.

Fecal Occult Blood Test (FOBT). This test detects the presence of blood in the stool, which is a warning sign for colorectal cancer. Many factors can interfere with the accuracy of this screening procedure, so follow-up testing is necessary to confirm positive results. If this method of screening is chosen, it is recommended that it be done once a year for people aged 50 to 80 years.

Flexible Sigmoidoscopy. For this test a thin, lighted tube is inserted into your rectum. With this device, your doctor can see about 27 inches into your colon, which is far enough to identify about 80 percent of cancers and polyps, because they tend to accumulate toward the lower end of your bowel. If this method of screening is chosen, it is recommended that it be done every five years for people aged 50 to 80 years.

Combination Flexible Sigmoidoscopy and FOBT. You and your doctor may decide to use both flexible sigmoidoscopy and FOBT to screen for colon cancer. This approach includes an annual FOBT and a flexible sigmoidoscopy every 5 years.

Total Colon Evaluation. A total colon evaluation can be done using a colonoscopy, colon X-ray alone, or a flexible sigmoidoscopy combined with a colon X-ray. A colonoscopy is similar to a flexible sigmoidoscopy, but allows your doctor to see the entire length of your colon. A colon X-ray or a flexible sigmoidoscopy combined with a colon X-ray is usually done every 5 years. A colonoscopy is usually done every 10 years.

Prevention

• Get screened for colorectal cancer. Ask your doctor which tests are right for you.
• Watch for warning signs. Talk to your doctor if you have black, bloody, or thin stools or if you have diarrhea or constipation that persists. Keep in mind that cancer is just one of many causes of these symptoms.
• Eat less fat. Obesity and diets that are high-fat or high-calorie have been linked to cancer in both animals and humans. By cutting down on fatty foods, you can also reduce your calorie intake.
• Eat more high-fiber foods. Foods high in fiber include whole-grain cereals and breads, beans, fruits and vegetables, potatoes, and brown rice.