Colorectal Cancer
Colorectal Cancer, malignancy of the large intestine , the lower portion of the intestinal tract, which consists of the colon and rectum. Although colon cancer can occur in any segment of the colon, it is most common in the sigmoid colon, the section closest to the rectum. Two simple tests can detect most colorectal tumors while they are still in an early, easy-to-treat stage. The first test is the digital rectal examination, during which the physician uses a gloved finger to gently check the smoothness of the rectal lining. The second test is the fecal occult blood test, in which a small sample of the patient’s feces is smeared on a card coated with a chemical called guaiac, which reacts with blood. The card is analyzed in a laboratory for occult (hidden) blood. A positive result does not necessarily indicate the presence of cancer. Although most colorectal cancers bleed, so do benign conditions such as hemorrhoids. Another test is fiberoptic sigmoidoscopy, in which a flexible instrum