The incidence of colorectal cancer (CRC) has increased in adults aged 40 to 54 years, whereas colonoscopy rates increased only for adults aged 45 to 54 years, suggesting a mismatch in colonoscopy trends and CRC incidence patterns, according to results from a study published in the Journal of Medical Screening.

Investigators analyzed changes in colonoscopy rates and CRC incidence in adults aged 40 to 54 using data from the National Health Interview Survey. The primary outcome was self-reported colonoscopy in the past year, which was surveyed every 2 to 3 years. Secondary outcomes were stool-based testing, sigmoidoscopy, or any CRC testing in the past year.

Most of the 53,175 respondents were white (70.9%), privately insured (73.1%), overweight or obese (67.5%), never smoked (56.1%), and did not report a family history of CRC (94.1%).

Linear trends for respondents aged 40 to 44 years were not significant between 2000 and 2015, except for a decline between 2010 and 2013. However, unadjusted past-year colonoscopy rates increased for respondents aged 45 to 49 years from 2.5% in 2000 to 5.2% in 2015 (absolute difference, 2.7%). From 2000 to 2015, colonoscopy rates increased from 5.0% to 14.1% for adults aged 50 to 54 (absolute difference, 9.1%).

Significant declines in stool testing in the previous year were noted between 2000 and 2015 across all age groups and recent sigmoidoscopy was uncommon and rates declined. However, CRC incidence rates rose by 28% in people aged 40 to 44, 15% in those aged 45 to 49, and 17% in those aged 50 to 54.

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“If the growing CRC incidence trend in those aged 40-54 had been the result of CRC testing, primarily with colonoscopy, reductions in late-stage CRC incidence and mortality would be expected,” the investigators noted. “However, distant stage CRC incidence rates increased between 2000 and 2015 for each age group, and nationwide data during 1998-2009 indicate that the most rapid increase among people aged under 50 was for distant stage disease.”

“Future studies should examine reasons for the rising CRC incidence rates in young adults, and monitor colonoscopy rates among adults aged 45-49 to assess the impact of recent American Cancer Society guidelines lowering the age of recommended screening,” concluded the authors.

Reference

Fedewa SA, Siegel RL, Jemal A. Are temporal trends in colonoscopy among young adults concordant with colorectal cancer incidence? [published online July 11, 2019]. J Med Screen. doi:10.1177/0969141319859608