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Signs and Symptoms of Colon Cancer

Article date: March 2, 2015

By Stacy Simon

It’s best to be tested for colon cancer before ever having any symptoms. Symptoms often appear only after the cancer has grown or spread. Colon cancer that’s found through screening – testing that’s done on people with no symptoms – is usually easier to treat. Screening can even prevent some colon cancers by finding and removing pre-cancerous growths called polyps.

However, if colon symptoms do occur, they can let you know you have a problem and should go to the doctor. Most of the time, these same symptoms are caused by something that isn’t cancer, such as infection, hemorrhoids, irritable bowel syndrome, or inflammatory bowel disease. Still, if you have any of these problems, it's important to see your doctor right away so the cause can be found and treated, if needed:

  • A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
  • A feeling that you need to have a bowel movement that is not relieved by doing so
  • Rectal bleeding, dark stools, or blood in the stool (often, though, the stool will look normal)
  • Cramping or abdominal (belly) pain
  • Weakness and fatigue
  • Unintended weight loss

Screening could save your life

Because colon cancer often doesn’t cause symptoms until it is advanced, the American Cancer Society recommends regular colon cancer screening for most people starting at age 50. People with a family history of the disease or who have certain other risk factors should talk with their doctor about beginning screening at a younger age. Several different tests can be used to screen for colon cancer. Talk with your doctor to find out which tests might be right for you.

When colon cancer is found early, before it has spread, the 5-year survival rate is 90%. This means 9 out of 10 people with early-stage cancer survive at least 5 years. But if the cancer has had a chance to spread outside the colon, survival rates are lower.

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How do they know if it’s cancer?

If your doctor finds something suspicious during a screening test, or if you have any of the symptoms associated with colon cancer, your doctor will probably recommend exams and tests to find the cause.

Your doctor may want to take a complete medical history to check for symptoms and risk factors, including your family history. As many as 1 in 5 people who develop colon cancer have other family members – especially parents, brothers and sisters, or children – who’ve had it. (Still, most colon cancers occur in people without a family history of it.) Having other colon problems can also increase risk. This includes pre-cancerous polyps, ulcerative colitis, Crohn’s disease, and hereditary syndromes such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (HNPCC), also known as Lynch syndrome. Having type 2 diabetes can also increase risk.

As part of a physical exam, your doctor will carefully feel your abdomen and also examine the rest of your body. You might also get certain blood tests to help determine if you might have colon cancer.

Your doctor may also recommend more tests, such as colonoscopy or an x-ray or CT scan of your colon. If colon cancer is strongly suspected, it is typically biopsied during a colonoscopy. In a biopsy, the doctor removes small pieces of tissue with a special instrument passed through the scope. The biopsy samples are then looked at under a microscope for cancer cells.

If you are diagnosed with colon cancer, treatment depends on how early it is found, but may include surgery, radiation, chemotherapy, and targeted therapies. It’s important for you to be able to talk frankly and openly with your doctor, and if you don’t understand something, to ask questions. Here is a list of questions to ask your doctor that you can take with you.

Reviewed by: Members of the ACS Medical Content Staff


ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases. For reprint requests, please contact permissionrequest@cancer.org.

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