Colon cancer is cancer in the lowest part of the digestive system, the large intestine or colon. Cancer occurs when cells in the body grow abnormally out of control. Most colon cancers occur when small, noncancerous (benign) clumps of cells called adenomatous polyps on the inner walls of the large intestine change and transform into cancerous (malignant) tumor over time. Identification of these benign polyps before they become cancerous is therefore especially important and can be done by regular screening tests.

Colon cancer cells lead to many complications by invading and damaging healthy tissues in the vicinity. Also, once malignant tumor form, the cancer cells may travel through the blood and lymph systems, eventually spreading to other parts of the body.

What are the signs & symptoms?

Symptoms of colon cancer depend on the size and location of cancer. There may be no obvious symptoms in the initial stages of the disease. However, symptoms increase in quantity and degree of severity as the disease progresses.

Colon cancer manifests itself in two forms, local (confined to the colon) and systemic colon cancer (cancer has spread to different parts of the body). There is a variation in the signs and symptoms of these two forms.

Local colon cancer symptoms

These symptoms include a change in bowel habits that include constipation or diarrhea, feeling of incomplete bowel evacuation, blood (either bright red or very dark) in stools, “pencil stools” (stools thinner than normal) and persistent abdominal discomfort accompanied by cramps, gas or pain. Consult your doctor right away if you are experiencing similar symptoms over a few days.

Systemic cancer symptoms

Characteristic symptoms of systemic cancer include unexplained weight loss, loss of appetite accompanied by fatigue or weakness, nausea, anemia and jaundice. If you experience any of these symptoms, you should be seen by your health care provider at the earliest.

What are the methods of screening?

Regular colon cancer screenings can detect colon cancer early and potentially save your life. Early detection is advisable as polyps or growths on the lining of the intestine can be found early and removed before they develop into cancer. Colon cancer screening is dreaded by many people as they think it might hurt or they find it embarrassing. It is important to understand your doctor performs these procedures on a regular basis and there is no need to feel embarrassed. Also, you will be kept comfortable during the procedure with anesthesia and not feel pain.

How is colon cancer diagnosed?

If your symptoms resemble colon cancer, your doctor will review your medical history and order blood tests. The following procedures may be recommended:

  • Colonoscopy: A long and flexible slender tube is attached to a video camera and monitor, and the entire colon is captured on a screen. This helps to detect suspicious areas from where biopsies (tissue samples) can be taken for analysis using surgical tools passed through the tube.
  • Virtual colonoscopy/CT colonography: Multiple CT scan images are combined to create a detailed picture of the inside of your colon. This is usually recommended for people who are unable to undergo colonoscopy.