Colorectal Cancer Screening Tests

Colorectal Cancer Screening Tests

Colorectal cancer screening is an important part of preventive health care. Regular screening is recommended for adults aged 50 and older, or earlier for those with a family history of the disease. Colorectal cancer screening tests are used to detect cancer or precancerous growth before they cause symptoms. This allows treatment to begin sooner and decreases the risk of death from the condition.


Screening tests for colorectal cancer may require different levels of preparation depending on the test. Before most colorectal cancer screenings, individuals should avoid certain medications such as iron supplements, anti-inflammatory drugs, aspirin, ibuprofen, and blood thinners. Additionally, people should be sure to follow their doctor’s dietary instructions.


Screening procedures for colorectal cancer include colonoscopy, sigmoidoscopy, fecal occult blood tests (FOBT) and stool DNA tests. During a colonoscopy, a doctor inserts a flexible tube with a small camera into the rectum and moves it through the entire large intestine. During a sigmoidoscopy, a doctor inspects the rectum and lower part of the colon. FOBT is a screening test used to detect the presence of blood in the stool. A stool DNA test looks for hidden genetic material from cancer cells in the stool.


  • Colonoscopy
  • Sigmoidoscopy
  • Fecal Occult Blood Test (FOBT)
  • Stool DNA Test


The risks of colorectal cancer screening tests vary according to the type of test. Common side effects of colonoscopy and sigmoidoscopy include abdominal pain, bloating, nausea, and constipation. During a colonoscopy, people may experience cramping and discomfort from the air that is pumped into the intestine. FOBT and stool DNA tests have minimal risks associated with them.

Why is Screening Necessary?

Colorectal cancer is the second leading cause of cancer deaths in the U.S. The American Cancer Society estimates that about 132,700 new cases and 51,200 deaths are expected to occur in 2020. Screening is the most effective way to detect colorectal cancer at its early stages, allowing for earlier diagnosis and treatment, and improving survival rates.

When to Screen

Neither the American Cancer Society nor the U.S. Preventive Services Task Force provides an exact timeline for when to start screening for colorectal cancer, but they do make recommendations for adults aged 50 and up. It is recommended that individuals at average risk begin colorectal cancer screenings at age 45. Those with a family history of colorectal cancer should begin screenings at a younger age. It’s also recommended that people continue colorectal cancer screenings until the age of 75.