What you should know about colon cancer and rectal cancer

What you should know about colon cancer and rectal cancer
Credit: Michigan Medicine.

Both colon cancer and rectal cancer are bowel cancer.

Although the two cancers have common symptoms and risk factors, they are different in location.

Karin Hardiman, M.D., Ph.D., surgical director of the Rogel Cancer Center’s Multidisciplinary Colorectal Cancer Clinic, talks about how to distinguish the two cancers.

What is rectal cancer?

The rectum is the last part of the large bowel before it opens into the anus. It is about 15cm long and can be divided into upper, middle and lower parts.

Rectal cancers often start in the innermost lining of the rectum as small growths or polyps.

The common symptoms include bleeding from the rectum, blood in the stool after a bowel movement, a change in bowel habits, a change in the shape or appearance of the stool and lower abdominal pain.

During the early stages of rectal cancer, patients may have no symptoms.

What is colon cancer?

Colon cancer is cancer of the large intestine (colon), which is the final part of the digestive tract. Like rectal cancer, colon cancer can begin as small, noncancerous (benign) polyps.

Common signs of colon cancer include a change in bowel habits, rectal bleeding or blood in your stool, long-term abdominal discomfort, a feeling that your bowel doesn’t empty completely, weakness and unexplained weight loss.

Why is it important to distinguish the two cancers?

According to the researcher, the rectum doesn’t have the same protective outer layer as the colon, so it’s easier for a tumor to break through and spread locally.

Research has shown that rectal cancer is 10 times more likely than colon cancer to come back after treatment.

The treatments for the two cancers are also different.

For rectal cancer, if it is advanced, the strategy is, to begin with, chemotherapy or targeted radiation to shrink the tumor.

Doctors then remove the radiated part of the rectum and reconnect the adjacent parts of the bowel. This can help maintain the surrounding organ function.

For colon cancer, doctors usually start with surgery because tumors in the colon pose less risk to nearby organs.

Rectal surgery is far more delicate and complex than colon surgery.

Both cancers require screening tests

No matter what type of cancer it is, the best chance of successful treatment is detecting it early through a screening test.

Research has shown that colonoscopy is very effective at early detection of cancer anywhere in the large bowel.

Doctors can find suspicious polyps and remove them through the test. In this way, about 90% of bowel cancer can be prevented.

So it is important to take colonoscopy as recommended.

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