Colorectal cancer is one of the most common cancers in the U.S. It is important to understand how colorectal cancer functions in the body and how it is diagnosed so that you can feel confident in your care if you or someone who know develops this disease.

Colorectal cancer 101

Ninety to 95 percent of all colorectal cancers are adenocarcinomas, which is a cancer that begins in cells that make and secrete fluids such as mucus. These cells are found in glandular tissue.

To better understand what an adenocarcinoma is, consider the word: Adeno means gland; carcinoma is a malignant tumor. Although these tumors are malignant, they generally start from adenomas – polyps that are not cancerous. The bigger the adenoma is, the more likely it is to become cancerous.

Colon polyps are a common occurrence. In fact, 25 percent of people over the age of 50 have polyps. It is important to remove these polyps to ensure they do not become cancerous.

Diagnosing colorectal cancer

If you are being examined for colorectal cancer, the first thing your doctor will do is review your medical history. He or she will conduct a thorough medical exam and then may conduct one or more of the following tests:

  • Digital rectal exam – This exam checks the rectum for lumps or abnormalities. About half of colon cancers can be detected in this way.
  • Fecal occult blood test – Blood in the stool can be an indicator of colorectal cancer. Your stool may also contain blood for other reasons not connected to colorectal cancer. If you experience blood in your stool, contact your healthcare provider.
  • X-ray of the large intestine or barium enema – An X-ray provides a picture of the colon and can help identify any polyps.
  • Colonoscopy – A colonoscopy is used to examine the bowel’s interior surface for abnormalities like polyps.
  • Biopsy – A biopsy allows the doctor to remove a tissue sample to then be sent to a pathologist for examination.
  • Virtual colonoscopy – This is a type of CT scan. It uses computer software along with CT imaging to examine the colon for polyps.

Stages of colorectal cancer

  • Stage 0: This is an extremely early stage. Abnormal cells are found only in the superficial layer of the colon wall. Stage 0 is also called carcinoma in situ.
  • Stage 1: This is an early stage. Cancerous cells have been found in the muscular layer of the colon wall, however, it has not spread beyond the colon wall.
  • Stage 2: Cancer has spread through the muscle layer of the colon wall to the outermost layer of the colon wall, but has not spread to the lymph nodes.
  • Stage 3: Cancer has spread to nearby lymph nodes but not to other parts of the body.
  • Stage 4: Cancer has spread beyond the colon to other parts of the body, most often the liver and lungs. This is an advanced stage.

Sarah Cannon, the Cancer Institute of HCA, recommends flexible sigmoidoscopy every five years or a colonoscopy every 10 years for those who are 50 years of age or older. Depending on your risk, there are alternative tests that can be conducted.

Speak with your healthcare provider about the right course of action for you.