Colon cancer is the third-most common cancer in both men and women in the United States. For men it is surpassed by prostate and lung cancer, and for women by breast and lung cancer. Though not preventable, colon cancer has a high cure rate when discovered early.
Incidence and Risk Factors
Colon cancer occurs most frequently in persons between the ages of 60 and 79 years. The male-to-female ratio is the same. Risk factors for colon cancer include polyps, some hereditary cancer syndromes (Lynch syndrome, familial adenomatous polyposis), ulcerative colitis and Crohn's disease. Low-fiber, high-fat diet has been postulated to contribute to the development of colon cancer, but this is yet to be confirmed by scientific data.
Symptoms
Colon cancer may grow for years before symptoms become noticeable. Symptoms of colon cancer vary according to location of the tumor within the colon. The colon is divided into the ascending colon, transverse colon and the descending colon. Malignant tumors that arise in the ascending colon present with anemia (low blood count), abdominal pain, blood in the stool and weight loss. Tumors in the descending colon tend to manifest with chronic constipation or bowel obstruction. Cancer in the transverse colon presents with a mixture of both sets of symptoms.
With the increased screening measures now in place, colon cancer is being discovered at early stages even before symptoms develop. The most common location for colon cancer is the sigmoid colon, which is the segment just before the rectum.
Tests
Colonoscopy is the test used to visualize the colon. It also allows the doctor to do a biopsy of any masses seen. If colon cancer is confirmed, other test such as a CT scan may be done to determine if the cancer has spread to any other organs. The American Cancer Society recommends screening for colon cancer beginning at age 50 years in persons with no identifiable risk factors. Screening involves a colonoscopy every ten years or a flexible sigmoidoscopy, which is similar to colonoscopy except it does not allow visualization of the entire colon, every five years. Alternatively, a fecal occult blood test (FOBT) can be done yearly. FOBT can be done at home, checking for blood in the stool. If this test is positive, then a colonoscopy must be done.
Treatment
The mainstay of treatment for colon cancer is surgery. Survival is increased when surgery is combined with chemotherapy and/or radiotherapy. Depending on the location of the cancer within the colon, a portion or all of the colon may be removed at the time of surgery.
Survivability
Colon cancer is a potentially curable disease. Stage I of the disease has a cure rate of above 95 percent. The American Cancer Society places emphasis on early detection via appropriate screening tests.
References
- Townsend, C. et al, Sabiston Textbook of Surgery
- American Cancer Society: What You Need to Know About Colon Cancer Screening
- Desch CE, Benson AB 3rd, Somerfield MR, et al. Colorectal cancer surveillance: 2005 update of an American Society of Clinical Oncology practice guideline. J Clin Oncol.
