What is colorectal cancer?

Colon cancer usually grows very slowly. It usually takes years to become large enough to cause symptoms. If the cancer is not removed and keeps growing, it eventually will destroy nearby tissues and then spread farther, first to nearby lymph nodes. From there it may spread to other parts of the body.

Colorectal cancer usually doesn't cause symptoms until after it has started to spread. The most common symptoms include blood in your stools and very dark stools. You may have more frequent bowel movements. Or you may feel like your bowels aren't emptying completely. Other symptoms may include belly or rectal pain.

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. Most people have surgery to remove the cancer. Chemotherapy, radiation therapy, or both may also be used. In some cases, targeted therapy or immunotherapy may be an option.

There are lifestyle actions you can take to lower some of the risk factors for colorectal cancer. These actions include the following:

• Maintain a healthy weight.
• Be physically active.
• Eat healthy foods, including vegetables, fruits, and whole grains. Avoid eating a lot of red meat or processed meats.
• If you smoke, get help to quit.
• If you drink alcohol, limit how much you drink.

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.

Health professionals who can evaluate your symptoms of colorectal cancer include:

• Family medicine physicians.
• General practitioners.
• Gastroenterologists.
• General surgeons and colorectal surgeons.
• Internists.
• Nurse practitioners.
• Physician assistants.

If your doctor thinks you may have colorectal cancer, your doctor may advise you to see a general surgeon or a colorectal surgeon. Colorectal cancer is treated by surgeons, medical oncologists, and radiation oncologists.

A risk factor for colorectal cancer is something that increases your chance of getting this cancer. Having one or more of these risk factors can make it more likely that you will get colorectal cancer. But it doesn't mean that you will definitely get it. And many people who get colorectal cancer don't have any of these risk factors.

Risk factors include:

Your age.

Getting older is a risk factor for colorectal cancer.

Your race.

African Americans have an increased risk of getting colorectal cancer (and dying from it) than people of other races.

Your family's medical history.

You are more likely to get colorectal cancer if one of your parents, brothers, sisters, or children has had a certain type of polyp or colorectal cancer.

Your medical history.

You may have an increased risk for getting colorectal cancer if you have:

• Had colorectal cancer in the past.
• Had one or more polyps removed from your colon.
• Ulcerative colitis or Crohn's disease.

• Inherited a gene change that increases your risk for colorectal cancer, such as Lynch syndrome or familial adenomatous polyposis (FAP).

Your lifestyle.

Certain lifestyle behaviors may increase your risk of colorectal cancer. These include:

• Smoking.
• Not getting enough physical activity.
• Drinking too much alcohol. This means more than 2 drinks a day if you're a man and more than 1 drink a day if you're a woman.
• Eating foods high in red and processed meats. And having a diet low in fruits, vegetables, and whole grains.

While you may not be able to control all risk factors, you may be able to lower your risk by taking steps to improve your overall health.

The exact cause of colorectal cancer is not known. Most cases begin in polyps, which are small growths inside the colon or rectum. Colon polyps are very common. Some polyps can turn into cancer. But if they are found early, usually through routine screening tests, they can be removed before they do.

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.