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What is Colorectal Cancer?

Dr. Allyson Ocean discusses colorectal cancer.

Allyson Ocean, M.D., New York Presbyterian Hospital

What is the difference between colon cancer and rectal cancer?

The difference between colon cancer and rectal cancer is that they’re both gastrointestinal cancers, but they are different parts of the lower colon. So the colon is the intestine – the large intestine. The rectum is the most posterior, lower part of the large intestine. Anatomically, they are two different areas and they’re treated in different ways.

What causes rectal cancer?

We do know what causes rectal cancer. Rectal cancer starts in a polyp. A polyp is an abnormal growth in the colon or the rectum and it can happen in either place of the large intestine and a polyp is a tissue that forms and then when that tissue undergoes mutations, the cells start to grow abnormally and then they start to invade into the muscle of the rectum; and that’s what cancer is. So cancer starts in a polyp.

Who can get rectal cancer?

The biggest risk factor for the development of rectal cancer is age. Young people can be affected, but the majority of patients are over age 50. Rectal cancer equally affects males and females and different races equally. Anyone can get rectal cancer; however, it is more seen in people who are over the age of 50. Actually, the average age of diagnosis in the United States recently was 72. So that’s why we screen people starting at age 50 with colonoscopies, so that we can find polyps, so that we can prevent rectal and colon cancer from forming.

Also, people that have a family history of rectal cancer are more likely to develop rectal cancer and they need to get screened at an earlier age. There are certain genetic syndromes that cause rectal cancer that can run in families- these include the hereditary polyp syndromes and the names are Lynch syndrome and also Familial Adenomatous Polyposis.

What are the symptoms of rectal cancer?

Typical symptoms of rectal cancer include rectal bleeding and a change in bowel habits, constipation and/or diarrhea.


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