What is colorectal cancer?

Colorectal cancer happens when cells that aren't normal grow in your colon. These cells often form in small growths called polyps. Not all colon polyps turn into cancer. But most colorectal cancer starts in a polyp. This cancer is also called colon cancer or rectal cancer, depending where the cancer is located.

Colorectal cancer in its early stages usually doesn't cause any symptoms. Symptoms occur later, when the cancer may be harder to treat. The most common symptoms include:

• Blood in your stool or very dark stools.
• A change in your bowel habits. (You may have more frequent bowel movements or a feeling that your bowels aren't emptying completely.)
• Low energy (fatigue).
• Pain in the belly or rectal pain.

If your doctor thinks you may have colorectal cancer, your doctor will ask you questions about your medical history. You may also have a physical exam. Other tests may include:

• A colonoscopy. Your doctor uses a lighted scope to view the inside of your entire colon.
• A biopsy. A sample of tissue taken from inside your colon. This may be done during your colonoscopy. Or a needle biopsy may be done to check for cancer in another part of your body.
• Blood tests, such as a complete blood count (CBC). These may be used to find the cause of symptoms like weakness, anemia, or weight loss.
• Imaging tests, such as a CT scan. These may be done to see if you have cancer in other places in your body.

Treatment for colorectal cancer is based on the stage and location of the cancer. It's also based on other things, such as your overall health. The main treatments are:

Surgery.

In most cases, the doctor removes part of the colon or rectum and sews the healthy ends back together. Sometimes a small area of cancer can be removed during a colonoscopy.

Chemotherapy.

These medicines kill fast-growing cells, including cancer cells and some normal cells. They may be given after surgery to help destroy any cancer cells that remain.

Radiation therapy.

This uses high-dose X-rays to destroy cancer cells and shrink tumors. It may be combined with surgery. Chemotherapy and radiation may be given together. (This is called chemoradiation.)

In some cases, targeted therapy or immunotherapy may be an option. A clinical trial may be a good choice.

Your doctor will talk with you about your options and then make a treatment plan.