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This topic will tell you about the initial testing, diagnosis, and treatment of colorectal cancer.

If you want to learn about colorectal cancer that has come back or has spread, see the topic Colorectal Cancer, Metastatic or Recurrent.

What is colorectal cancer?

Colorectal cancer happens when cells that are not normal grow in your colon or rectum. These cells grow together and form tumors.

This cancer is also called colon cancer or rectal cancer. It is the third most common cancer in the United States. And it occurs most often in people older than 50.

When it is found early, it is easily treated and often cured. But because it usually is not found early, it is the second leading cause of cancer deaths in the United States.¹ Fairly simple screening tests can prevent this cancer, but fewer than half of people older than 50 are screened. According to the American Cancer Society, if everyone were tested, tens of thousands of lives could be saved each year.

What causes colorectal cancer?

Most cases begin as polyps, which are small growths inside the colon or rectum. Colon polyps are very common, and most of them do not turn into cancer. But doctors cannot tell ahead of time which polyps will turn into cancer. This is why people older than 50 need regular tests to find out if they have any polyps and then have them removed.

What are the symptoms?

Colorectal cancer usually does not cause symptoms until after it has begun to spread. See your doctor if you have any of these symptoms:

• Pain in the belly
• Blood in your stool or very dark stools
• A change in your bowel habits, such as more frequent stools or a feeling that your bowels are not emptying completely

How is colorectal cancer diagnosed?

If your doctor thinks that you may have this cancer, you will need a test, called a colonoscopy, that lets the doctor see the inside of your entire colon and rectum. During this test, your doctor will remove polyps or take tissue samples from any areas that don't look normal. The tissue will be looked at under a microscope to see if it contains cancer.

Sometimes other tests, such as a barium enema or a sigmoidoscopy, are used to diagnose colorectal cancer.

How is it treated?

Surgery is almost always used to treat colon and rectal cancer. The cancer is easily removed and often cured when it is found early.

If the cancer has spread into the wall of the colon or farther, you may also need radiation or chemotherapy. These treatments have side effects, but most people can manage the side effects with medicines or home care.