The US Preventive Services Task Force (USPSTF) has issued an updated guideline with recommendations regarding screening for colorectal cancer (CRC). A systematic review found that screening can be of “substantial net benefit.”
CRC remains the second leading cause of cancer death in the United States, with about 134,000 new cases expected to be diagnosed this year. The previous USPSTF recommendation, issued in 2008, offered specific testing guidelines and intervals; the update focuses more on the need to increase screening generally, given that multiple testing strategies can be of benefit.
The review covered several screening modalities, including: colonoscopy, flexible sigmoidoscopy; CT colonography; guaiac-based fecal occult blood test; fecal immunochemical test; multitargeted stool DNA test; and the methylated SEPT9 DNA test.
The primary recommendation from the review is that all asymptomatic adults deemed to be at average risk for CRC aged 50 to 75 years should undergo screening of varying intervals depending on the test used. For adults aged 76 to 85, the decision to continue screening should be an individual one that takes into account specific overall health and prior screening history. The full recommendation was published online yesterday in JAMA.
The recommendation to screen in the younger group is considered an “A recommendation,” meaning the USPSTF found with high certainty that the net benefit is substantial. They found no evidence that any single screening test provides greater net benefit than the others; specifically, the life-years gained with non-colonoscopy tests were within 90% of those gained with colonoscopy.
For example, flexible sigmoidoscopy administered every 5 years yielded 221 life-years gained per 1,000 people screened using a “middle” model estimate. For CT colonography every 5 years, this number was 248 life-years gained; for the guaiac-based fecal occult blood test administered annually it was 247 life-years.
CRC deaths avoided per 1,000 people screened were also similar between tests. For example, for CT colonography every 5 years there were 22 deaths averted, again using the “middle estimate.” For fecal immunochemical test conducted annually, 22 deaths were averted. The USPSTF also noted that no particular test avoided the harms associated with testing better than the others.
The secondary recommendation regarding those aged 76 to 85 years received only a “C” rating, meaning there is at least moderate certainty that the net benefit to screening is small.
“Screening for colorectal cancer is a substantially underused preventive health strategy in the United States,” the authors wrote. “Accordingly, the best screening test is the one that gets done, and the USPSTF concludes that maximizing the total proportion of the eligible population that receives screening will result in the greatest reduction in colorectal cancer deaths.”