Colorectal cancer: Task force affirms values of screening for all after 50, some after 76

Colorectal cancer screening by a variety of methods is worthwhile and recommended for all adults aged 50-75 years, according to the latest recommendations from the US Preventive Services Task Force.

In addition, the USPSTF recommended selective screening for older adults aged 76-85 years, depending on their health status and screening history.

A team of researchers of Kaiser Permanence in Portland, Ore., reviewed studies on colorectal cancer screening published between Jan. 1, 2008, and Dec. 31, 2014, with surveillance continuing through 2016.

The USPSTF’s last recommendations on colorectal cancer screening were released in 2008.

“Although CRC screening has a large body of supporting evidence, additional research is still needed to weigh the relative benefits and harms of each test within a program of screening” for average-risk adults.

The final recommendation statement includes three screening options that carry over form the 2008 guidelines: colonoscopy, sigmoidoscopy, and fecal immunochemical testing (FIT) with occult blood.

Other options now recommended include computed tomographic colonography (CTC), fecal immunochemical tests with DNA (FIT-DNA), guaiac-based fecal occult blood testing (gFOBT), and sigmoidoscopy plus FIT.

Some highlights from the analysis: Four randomized trials including 458,002 patients showed that one-time or two-time screening with flexible sigmoidoscopy was associated with decreased mortality from colorectal cancer, compared with no screening.

In addition, the researchers found that CTC had 73%-98% sensitivity and 89%-91% specificity to detect adenomas 6 mm and larger, compared with colonoscopy in seven studies.

However, the risk of harm from low-dose ionizing radiation remains a consideration.

For diagnostic accuracy, colonoscopy showed per-person sensitivity for 89%-98% for adenomas 10 mm or larger, and 75%-93% for adenomas 6 mm or larger, in studies comparing it with CTC or as an adjunct to CTC.

However, studies showing applicability to community practices were limited.

Fecal immunochemical tests (FITs) showed sensitivity ranging from 73% to 88% and specificity from 90% to 96%.

Data from five randomized, controlled trials evaluating multiple rounds of biennial screening using gFOBT showed a significant reduction in colorectal cancer mortality, from a relative risk of 0.91 at 19.5 years to a relative risk of 0.78 at 30 years.

Colonoscopy remains the standard by which other tests are assessed, although it has the highest risk of procedural complications.

Three new randomized, controlled trials involving screening colonoscopy in average-risk adults scheduled for completion in 2021, 2026, and 2027, may yield more information on incidence and mortality.

The evidence report and review was limited by its focus on average-risk adults; it did not address factors including screening for high-risk adults, availability and access to tests, potential risks of overdiagnosis, and overuse of screening after adenoma detection.

In addition, “data are still needed on the differential uptake of and adherence to screening modalities and on continued adherence to repeated rounds of screening and diagnostic follow-up to screening over longer periods.”

However, they concluded, “colonoscopy, flexible sigmoidoscopy, CTC, and various stool tests have differing levels of evidence to support their use in CRC screening, ability to detect CRC and precursor lesions, and risk of serious adverse events in average-risk adults.”