What Is Rectal Cancer?
Rectal cancer forms in the tissues of the rectum, which is the last several inches of the large intestine before the anus (the opening of the large intestine to the outside of the body). Most of the large intestine is called the colon.
Rectal cancer usually develops over years, starting with precancerous growths called polyps. Some polyps grow to penetrate the wall of the rectum.
Different types of cancer can develop in the rectum. Most rectal cancers are adenocarcinomas, which are cancers from glandular tissue. Other cancer types that can occur in the rectum include carcinoid tumors, small cell carcinomas, and gastrointestinal stromal tumors (GIST).
The focus of this information is on rectal cancers that are adenocarcinomas.
Colon and rectal cancers are the fourth most common cancers diagnosed in the United States. Survival after diagnosis has been gradually increasing in the past decade for several reasons, including:
- Screening programs can catch the disease in its pre-cancerous or early stages, which are more curable.
- Increasingly, there are better therapies – both surgical techniques and chemotherapies, including targeted therapies.
Our team has been a leader in clinical trials for various treatments for rectal cancer, to improve outcomes for patients and survivors.
When detected early, rectal cancer is a very treatable form of cancer. The earlier that it is found, the more likely that it will be cured. As the cancer becomes more advanced, the cure rate declines, but it may still be treatable for long periods of time.
Most rectal cancers start as polyps, or growths. Over time, some, but not all, polyps change into cancers. Polyps that have a higher risk becoming cancer are known as adenomas.
- Screening is extremely important, because finding polyps before they become cancerous reduces the risk of developing rectal cancer by at least 90 percent.
- Finding ways to prevent polyps from forming is an important part of ongoing research at Dana-Farber Brigham Cancer Center.