Colon Cancer
Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States (not including skin cancers). The American Cancer Society's most recent estimates for the number of colorectal cancer cases in the United States are for 2011: 101,700 new cases of colon cancer 39,510 new cases of rectal cancer.
WHO IS AT RISK?
Overall, the lifetime risk of developing colorectal cancer is about 1 in 20 (5.1%). This risk is slightly lower in women than in men. A number of other factors might also affect a person's risk for developing colorectal cancer. Colorectal cancer is the third leading cause of cancer-related deaths in the United States when men and women are considered separately, and the second leading cause when both sexes are combined. It is expected to cause about 49,380 deaths during 2011. The death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping in both men and women for more than 20 years. There are a number of likely reasons for this. One is that polyps are being found by screening and removed before they can develop into cancers. Screening is also allowing more colorectal cancers to be found earlier when the disease is easier to cure. In addition, treatment for colorectal cancer has improved over the last several years. As a result, there are now more than 1 million survivors of colorectal cancer in the United States.
Though colorectal cancer may occur at any age, more than 90% of the patients are over age 40, at which point the risk doubles every ten years. In addition to age, other high risk factors include a family history of colorectal cancer and polyps and a personal history of ulcerative colitis, colon polyps or cancer of other organs, especially of the breast or uterus. The majority of patients who develop colon cancer, however, have no high risk factors.
HOW DO COLON CANCERS FORM?
It is widely thought that the majority of colon cancers begin as noncancerous polyps. These growths form on the bowel wall, increase in size, and eventually become invasive cancers. By removing noncancerous polyps it is thought that colon cancers can be prevented.
CAN COLON CANCER BE PREVENTED?
There are steps that reduce the risk of contracting the disease. One way is having benign polyps removed by an outpatient procedure called colonoscopy. In some cases polyps can not be removed by colonoscopy for technical reasons. In these situations, that portion of the colon my need to be removed surgically. In most cases this can by done using a minimally invasive procedure called laparoscopic colectomy. Though not definitely proven, there is some evidence that diet may play a significant role in preventing colorectal cancer. As far as we know, a high fiber, low fat diet is the only dietary measure that might help prevent colorectal cancer. Advice from the American Cancer Society on diet and exercise.
WHAT ARE THE SYMPTOMS?
Unfortunately, the most common symptom of colon polyps and colon cancer is no symptoms at all! When patients have symptoms, the most common symptoms are rectal bleeding and changes in bowel habits, such as constipation or diarrhea. (These symptoms are also common in other diseases so it is important you receive a thorough examination should you experience them.) Abdominal pain and weight loss are usually late symptoms indicating possible extensive disease. The lack of symptoms in most patients with polyps and early cancers makes screening tests pivotal to diagnosing this cancer in a curable stage. (Click for link to American Cancer Society colon cancer screening recommendations)
HOW IS COLORECTAL CANCER TREATED?
Colorectal cancer requires surgery in nearly all cases for complete cure. Radiation and chemotherapy are sometimes used in addition to surgery. Between 80-90% are restored to normal health if the cancer is detected and treated in the earliest stages. The cure rate drops to 50% or less when diagnosed in the later stages. Thanks to modern technology, less than 5% of all colorectal cancer patients require a colostomy, the surgical construction of an artificial excretory opening from the colon. Tranditionally colon cancer surgery has been done using an open technique - open colectomy. Over the past several years an increasing number of colon cancers have been removed using a minimally invasive technique called laparoscopic colectomy. In the past, there was suspicion that the cure rate for laparoscopic colectomy was not as high as with traditional open techniques. An increasing number of recent studies have shown that in the well selected patient, the cure rate for the laparoscopic approach is as good as with the more invasive open techniques.
ADDITIONAL INFORMATION
University of South Carolina American College of Gastroenterology