The recommended age for colonoscopy and other colon cancer screenings is being updated with the starting age for people with average risk factors dropping to 45 from 50.

Published: April 14, 2021 | Updated: March 15, 2023

The recommended age for colonoscopy and other colon cancer screenings is increasingly considered to be 45 for those at average risk, five years earlier than the previous guidance.

The risk of developing colon cancer is lower in adults under 50, but recent trends have shown that risk increasing, according to the U.S. Preventive Services Task Force (USPSTF).

Norton Healthcare has adopted a practice of recommending colonoscopies starting at age 45 for those at average risk. Average risk means an individual doesn’t have a family history that increases their risk and hasn’t been diagnosed previously with colon cancer or other conditions that increase their risk.

Existing guidance from the U.S. Multi-Society Task Force on Colorectal Cancer varies somewhat from the USPSTF and recommends those at increased risk start screening 10 years prior to the age a relative was diagnosed or age 40 — whichever is earlier. This applies to anyone with a first-degree relative (parent, offspring or sibling) under age 60 with colon cancer or advanced polyps, or multiple first-degree relatives of any age with a diagnosis.

“If your family member had cancer at 50, you should be screened at 40; and if you have multiple relatives, even primary first-degree relatives with polyps, it’s recommended you start now at 40 for just screening,” said Ryan K. Jones, M.D., colon and rectal surgeon with Norton Surgical Specialists – Colorectal Health.

Those with inflammatory bowel disease such as ulcerative colitis and Crohn’s disease face a higher risk and also need to begin screening earlier.

Thanks to screening, overall incidence of colon cancer is decreasing, but for people under 50, colon cancer is increasing, according to Michelle Julien, M.D., colon and rectal surgeon also with Norton Surgical Specialists – Colorectal Health.

Family history is a major risk factor especially with closer relatives. Other risk factors include the typical Western Hemisphere diet of high intake of red meat, sugar, fat, salt and refined grains; obesity, heavy alcohol use and smoking.

Traditional colon cancer screening guidelines called for tests at 10-year intervals because that is approximately how long it takes from initiation of cell changes to becoming cancerous.

Some patients need to be screened more often. For example, having polyps previously raises the risks of having polyps again and requires more frequent screening, according to Dr. Jones.

The gold standard for screening is a colonoscopy with a full bowel prep because you can screen, diagnose with a biopsy and treat at the same time.

Flexible sigmoidoscopies, which examine the rectum and sigmoid colon – a short curve of the large intestine just before the rectum – are within guidelines under certain circumstances but would require more frequent testing and immunohistochemical fecal tests.

Flexible sigmoidoscopies are better suited to younger patients, particularly in the 40- to 45-year-old range because colon cancers in this age group tend to develop in the sigmoid colon, according to Dr. Julien.

Pros and cons of different types of screening tests

Other noninvasive tests that can be done at home are fecal immunochemical test (FIT), fecal occult blood tests and stool DNA testing. Of these, the stool DNA test such as Cologuard is considered the best of the lesser options, with a detection rate of more than 90% for having a cancer.

Cologuard can miss 50% of even advanced polyps and offer false assurances even if the test is done every three years.

Positive results on any of these tests still mean a follow-up colonoscopy for evaluation and possible treatment.

“At the end of the day, if it’s a positive fecal test, you’re still going to have to go down the road of needing a colonoscopy,” Dr. Julien said.

Insurance coverage typically is for only one type of screening annually, meaning a colonoscopy following a positive Cologuard or other test would be considered a diagnostic and therapeutic intervention, not a screening, according to Dr. Julien.

Computed tomography (CT) colonography has a high sensitivity, but requires a bowel prep like a colonoscopy and, like the fecal tests, requires treatment with a colonoscopy if it shows any abnormalities. It also can be uncomfortable because air is put in the colon.

For patients who have a primary or secondary relative diagnosed with either polyps or colon cancer, only a colonoscopy is recommended.

Traditionally, screening stopped at age 80, but it has become more targeted to the individual.

“The guidelines have gotten away from a specific age, and I think it’s more of a patient-based decision,” Dr. Jones said.