A study found that after the American Cancer Society (ACS) released updated colorectal cancer screening guidelines in May 2018 that lowered the age at which individuals should begin screening — from 50 years to 45 years — rates of screening increased among individuals aged 45 to 49 years. The findings were recently published in Cancer.

To assess the effect of the updated May 2018 guides, the study researchers extracted results from the 2018 National Health Interview Survey, to which 64.2% of individuals responded. Individuals were excluded if screening data were unavailable or if a history of CRC was known. The study included 5800 individuals, and CRC screening within the prior year were calculated. Possible screening methods included colonoscopy, sigmoidoscopy, computed tomography colonography, and stool testing. 

CRC screening rates were grouped according to individual age (45-49 years, 50-54 years, and 55-59 years) and when the survey was conducted in 2018. The timing of the survey was labeled by quarter, with January through March being quarter 1, April through June being quarter 2, July through September being quarter 3, and October through December being quarter 4. 

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The study revealed that in quarter 1, which was before the guidelines were released, 4.8% of individual aged 45 to 49 underwent CRC screening, and this rate increased in quarters 2 (6.6%), 3 (8.8%), and 4 (11.7%), a trend that was statistically significant (linear P =.003). No such statistically significant trend was seen across quarters for patients aged 50 to 54 years or 55 to 59 years.

The study researchers described this quarterly increase as “coinciding with the release of ACS guidelines,” but cautioned that it is “unknown” whether this trend will be sustained because commercial health insurers are only required to cover screening among average-risk individuals beginning at age 50 years, which is consistent with the US Preventive Services Task Force recommendations. 

In addition, the individuals who “quickly” adopted the updated guidelines may have already been at “above-average” risk for the disease. 


  1. Fedewa SA, Siegel RL, Goding Sauer A, Bandi P, and Jemal A. Colorectal cancer screening patterns after the American Cancer Society’s recommendation to initiate screening at age 45 years [published online December 18, 2019]. Cancer. doi: 10.1002/cncr.32662