Understanding colon cancer screening guidelines

doctor explaining colon cancer screening guidelines to patient

Colorectal cancer, often shortened just to colon cancer, is the third most commonly diagnosed cancer in the United States aside from skin cancers. While there are treatments available, including radiation and chemotherapy, the most important aspect of successful treatment is early detection — which is why knowing the colon cancer screening guidelines is essential.

While colon cancer can impact individuals of any age, it is more common in older adults. However, some people are considered to be at a higher risk and should begin screening earlier. Below, we’ll delve into the colon cancer screening guidelines, as well as signs and symptoms, and what to know about staging.

Colon cancer screening guidelines

The screening guidelines for colon cancer are dependent on whether an individual is considered to be at average or high risk. A person at average risk for colon cancer is someone who has not had a history of colon cancer in their family, does not have ulcerative colitis or Crohn’s disease, and does not have a suspected hereditary condition that could lead to colon cancer. An individual is considered high risk if they do have a family history of colon cancer, ulcerative colitis or Crohn’s disease, or a known family history of hereditary conditions that can lead to colon cancer.

For individuals at an average risk level, it is recommended to start screening at the age of 45, and continue through 75. Individuals 76 to 85 years old should work with their doctors to determine the appropriate screening cadence, and individuals over 85 are not recommended to receive screening. For those that are at high risk, it is recommended to start screening for colon cancer at the age of 40, or ten years earlier than the earliest diagnosis in the family history, whichever comes first. 

Colon cancer signs

Colon cancer symptoms vary greatly and often do not present at all, which is part of the reason why screening and early detection are so important. Most commonly, individuals experience symptoms such as persistent abdominal discomfort, changes in bowel habits, fatigue, and unexplained weight loss, but these typically do not occur until the cancer has progressed into its later stages.

Colon cancer stages

The stages of colon cancer are determined by the size and depth of the tumor, the spread to nearby lymph notes, and the spread to more distant parts of the body. Doctors use all of this information to determine what stage the colon cancer is, and all the stages are listed below.

  • Stage 0 means that cancer cells are only found in the inner lining of the organ
  • Stage I cancer has grown into the muscular layer of the colon or rectum, but has not spread into nearby tissue or lymph nodes
  • Stage IIA cancer has grown through the organ walls but has not spread to nearby tissue or to the nearby lymph nodes
  • Stage IIB cancer has grown into the lining of the abdomen, but not to other nearby tissue or lympn nodes
  • Stage IIC means that a tumor has grown into nearby structures, but not other tissue or lymph nodes
  • Stage IIIA cancer has grown through the inner lining or into the muscle layers of the intestine. It has also spread to up to three lymph nodes but has not to other parts of the body
  • Stage IIIB cancer has spread to surrounding organs and into up to three three lymph nodes
  • Stage IIIC means that regardless of the size of the tumors, the cancer has spread to four or more lymph nodes but not to any distant parts of the body
  • Stage IVA cancer has spread to a single distant part of the body
  • Stage IVB cancer has spread to more than one part of the body
  • Stage IVC cancer has spread to the peritoneum and may also be at other sites or organs

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