What You Need to Know About Colon Cancer

Why screening could save your life, plus tips for lowering your risk.

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Colon cancer is the third leading cause of cancer-related deaths in American men and women separately, and the second most common cause of cancer deaths when men and women are combined. This disease is so often deadly because it’s frequently discovered after it’s already reached a late stage.

“Colon cancer is potentially very curable if we screen for it according to guidelines,” says Steven Goldin, MD, a surgical oncologist at Fawcett Memorial Hospital in Port Charlotte, Florida. 

Here’s how to recognize the signs of colon cancer, when to book your next screening appointment, plus tips to lower your risk.

Symptoms of colon cancer

Colon cancer begins in the lower part of your intestine. “Most colon cancers, especially the smaller tumors, have no symptoms at all,” says Goldin. “People will be walking around with no idea that they have multiple tumors. Often, they don’t get tested until there’s not much that can be done to treat them.”

By the time symptoms show, the disease has usually already spread outside of the colon. Yet, between 70 to 90 percent of colon cancers are diagnosed after symptoms appear because of the tendency to put off screening.

If symptoms are present, they may include:

  • Black or tarry stools, diarrhea
  • Severe constipation or being completely unable to have a bowel movement
  • Frequent gas pain or stomach aches
  • Blood in your stool: “Anybody who's experiencing rectal bleeding should make an appointment with their healthcare provider (HCP). People might think, ‘Well, I've got hemorrhoids,’ but you could have colon cancer as well,” says Goldin.

Internal bleeding can also cause you to feel weak, exhausted or dizzy. If you’re experiencing any of these symptoms, make an appointment with your HCP immediately.

Colon cancer screening

If you’re at an average risk for colon cancer, you should begin screening at age 45. People who are at a higher risk should talk to their HCP by age 40 to determine an appropriate screening regimen for them, says Goldin. You’re at a higher risk and may need to start screening before age 45 if you:

There are a number of tests available, but the gold standard for colon cancer screening is the colonoscopy, explains Goldin. For a colonoscopy, a gastroenterologist, a doctor specializing in the stomach and intestines, will advance a long tube with a camera through your colon to search for polyps. Polyps are little growths on the colon lining, which may eventually grow into tumors.

If you have polyps, your gastroenterologist will remove samples and send them to a lab to determine if you have cancer, called a biopsy. He or she may be able to completely remove polyps or even small tumors during the colonoscopy as well.

What can you expect if you’re scheduled for a colonoscopy?

The night before, you’ll need to complete a bowel prep, which involves drinking a liquid medication that causes short-term diarrhea. The goal of bowel prep is to clean out your lower intestine so the lining of your colon is easier to see on camera. You may also need to avoid solid foods ahead of time. Most people are instructed to only consume clear liquids like chicken broth and Jell-O the day before.

Right before your colonoscopy, you’ll be given a sedating medication, or a drug that will make you feel calm and sleepy. You may still be groggy afterwards, so bring a friend or family member along to help you get home safely.

If you’re at an average risk for colon cancer, your next colonoscopy should be done in ten years.

How colon cancer is treated

Most labs will know your biopsy results within two weeks, but many will notify you sooner. If your biopsy reveals that you have cancer, the treatment that you receive will depend on how aggressive the cancer is.

Small tumors may be completely removed during your initial colonoscopy. If it’s not possible to completely remove the cancer at that point, you may need surgery as well. Your surgeon will take samples of lymph nodes during surgery to determine whether the cancer has spread outside of your colon.

If the cancer has reached your lymph nodes, he or she may recommend chemotherapy. Chemotherapy is a type of medication that kills off cancer cells that may be left in your body after surgery. Chemo for colon cancer typically involves intravenous medication that’s given in a series of doses, spread out over about six months.

Ways to lower your risk for colon cancer

There’s no surefire way to prevent colon cancer, but there are a few lifestyle changes that can help lower your risk:

  • Quit smoking: Follow Sharecare’s ten-step quit smoking plan to help you kick the habit.
  • Eat less red meat: “There’s growing evidence that red meat and smoked foods, which have been processed with preservatives called nitrites, can increase your risk for colon cancer,” says Goldin. Set a goal to cook a few vegetarian meals each week. Add legumes like beans, lentils and chickpeas to dishes instead of meat to help you feel full and satisfied.
  • Get enough exercise: Aim for 150 minutes of moderate exercise or 75 minutes of vigorous exercise each week. Keeping the weight off—especially around your midsection—has been shown to reduce colon cancer risk.

The most important thing you can do to avoid a late-stage colon cancer diagnosis is to follow routine screening guidelines.

“Think about the costs of treatment, the worry and everything you’d go through with a colon cancer diagnosis,” says Goldin. “If you detect polyps early and remove them before they become cancer, you can prevent a great deal of pain and worry.”

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