Colonoscopy in the news
Abnormal growth in the colon or rectum
In most people, colorectal cancers develop slowly over 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.
Start and spread of colorectal cancer
If cancer forms within a polyp, it can eventually begin to grow into the wall of the colon or rectum. When cancer cells are in the wall, they can then grow into blood vessels or lymph vessels. Lymph vessels are thin, tiny channels that carry away waste and fluid. They first drain into nearby lymph nodes, which are bean-shaped structures that help fight infections. Once cancer cells spread into blood or lymph vessels, they can travel to nearby lymph nodes or to distant parts of the body, such as the liver. Spread to distant parts of the body is called metastasis. Cancer limited only to the polyp can be cured in up to 100% of cases. On the other hand metastatic cancer can be cured in less than 6% of cases.
Importance of colorectal cancer screening
The American Cancer Society’s most recent estimatests the lifetime risk for developing colorectal cancer is about 1 in 20 (5.1%). Colorectal cancer is the second leading cause of cancer-related deaths in the United States in men and women combined.
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 also allows more colorectal cancers to be found earlier, when the disease is easier to cure.
Regular colorectal cancer screening or testing is one of the most powerful weapons for preventing colorectal cancer. Screening is the process of looking for cancer in people who have no symptoms of the disease. Colonoscopy is the only test available to both detect and successfully remove colorectal polyps.
Finding colorectal cancer early
Colorectal cancer is often found after symptoms appear, most people with early colon or rectal cancer have no symptoms of the disease. Symptoms usually appear only with more advanced disease. This is why getting the recommended screening colonoscopy before any symptoms develop is so important. Regular screening can often find colorectal cancer early, when it is most likely to be curable. In many cases, screening can also prevent colorectal cancer altogether. This is because some polyps, or growths, can be found and removed before they have the chance to turn into cancer.