March is colon cancer awareness month. Dr. Howard Monsour joined my for a brief discussion of colon cancer screening strategies. Download the audio segment and listen along. Download Colon cancer segment .
Here are some basic facts on colon cancer from the American Cancer Society:
In most people, colorectal cancers develop slowly over a period of several years. Before a cancer develops, a growth of tissue or tumor usually begins as a non-cancerous polyp on the inner lining of the colon or rectum. A tumor is abnormal tissue and can be benign (not cancer) or malignant (cancer). A polyp is a benign, non-cancerous tumor. Some polyps can change into cancer, but not all do. The chance of changing into a cancer depends upon the kind of polyp:
- Adenomatous polyps (adenomas) are polyps that have the potential to change into cancer. Because of this, adenomas are called a pre-cancerous condition.
- Hyperplastic polyps and inflammatory polyps, in general, are not pre-cancerous. But some doctors think that some hyperplastic polyps can become pre-cancerous or might be a sign of having a greater risk of developing adenomas and cancer, particularly when these polyps grow in the ascending colon.
Another kind of pre-cancerous condition is called dysplasia. Dysplasia is an area in the lining of the colon or rectum where the cells look abnormal (but not like true cancer cells) when viewed under a microscope. These cells have the potential to change into cancer over time. This is usually seen in people who have had diseases such as ulcerative colitis or Crohns disease for many years. Both ulcerative colitis and Crohns disease cause chronic inflammation of the colon.
Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that about 108,070 new cases of colon cancer (53,760 in men and 54,310 in women) and 40,740 new cases of rectal cancer (23,490 in men and 17,250 in women) will be diagnosed in 2008.
Overall, the lifetime risk for developing colorectal cancer is about 1 in 19 (5.4%). This risk is slightly higher in men than in women. A number of other factors (described in the section, "Risk factors for colorectal cancer") may also affect a person's risk.
Colorectal cancer is the third leading cause of cancer-related deaths in the United States when men and women are considered seperately, and the second leading cause when both sexes are combined. It is expected to cause about 49,960 deaths (24,260 men and 25,700 women) during 2008.
The death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping 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.
One of the most powerful weapons in preventing colorectal cancer is regular colorectal cancer screening or testing. Regular colorectal cancer screening can, in many cases, prevent colorectal cancer altogether. This is because most colorectal cancers start as polyps, which are non-cancerous growths in the lining of the colon or rectum. From the time the first abnormal cells start to grow, it usually takes about 10 to 15 years for them to develop into colorectal cancer. Testing often finds these polyps, and allows them to be removed before they have the chance to turn into cancer. Screening can also result in finding colorectal cancer early, when it is highly curable.
There are several tests used to screen for colorectal cancer in those with an average risk of colorectal cancer. Ask your doctor which tests are available where you live and which option is best for you. People who have no identified risk factors (other than age) should begin regular screening at age 50. Those who have a family history or other risk factors for colorectal polyps or cancer (see below) should talk with their doctor about starting screening at a younger age and/or getting screened at more frequent intervals.
