Colon and Rectal Cancer
Another common cancer in the United States is colon and rectal cancer (also called colorectal cancer). Colorectal cancer is the third most common type of cancer in both men and women. Age is a key risk factor, with more than 91% of cases diagnosed in people age 50 and older. Many cancers arise from preexisting polyps, small growths on the wall of the colon that may gradually develop into malignancies. Many colon cancers may be due to inherited gene mutations.
Lifestyle also affects colon cancer risk. Regular physical activity reduces risk; obesity increases risk. Although the mechanisms are unclear, high intake of red meat, smoked meat and fish, refined carbohydrates, and simple sugars appears to increase risk, as do excessive alcohol consumption and smoking. Protective lifestyle factors may include a diet rich in fruits, vegetables, and whole grains; adequate intake of folic acid, calcium, magnesium, and vitamin D; regular use of nonsteroidal anti-inflammatory drugs such as aspirin and ibuprofen; and, in women, use of oral contraceptives.
Colon and Rectal Cancer Photo Gallery
Chemotherapy The treatment of cancer with chemicals that selectively destroy cancerous cells.
Mammogram A low-dose X-ray of the breasts used for the early detection of breast cancer.
Biopsy The removal and examination of a small piece of body tissue for the purpose of diagnosis.
Ultrasonography An imaging method in which inaudible high-pitched sound (ultrasound) is bounced off body structures to create an image on a monitor.
Prostate-specific antigen (PSA) blood test A diagnostic test for prostate cancer that measures blood levels of prostate-specific antigen (PSA).
Young polyps and early-stage cancers can be removed before they spread. Because polyps may bleed, the standard warning signs of colon cancer are bleeding from the rectum and a change in bowel habits. The ACS recommends that regular screening be started at age 50. A yearly stool blood test can detect traces of blood in the stool long before obvious bleeding can be noticed. Another test is the colonoscopy, in which a flexible fiber-optic device is inserted through the rectum, allowing the colon to be examined and polyps to be removed (Figure 12.3). Studies show that screening could reduce the occurrence of colorectal cancer by up to 90%, but only about one-half of adults undergo these tests.
Surgery is the primary method of treatment for colon and rectal cancer. The five-year survival rate is 90% for colon and rectal cancers detected early and 64% overall.
