Trends in colonoscopy rates did not fully align with the increase in colorectal cancer (CRC) in younger adults, adding to evidence that the rise in early onset CRC is not solely a result of more detection. The study, ‘Are temporal trends in colonoscopy among young adults concordant with colorectal cancer incidence?’ was published in the Journal of Medical Screening.
In the US, colorectal cancer incidence has increased in adults under age 55 and the study investigators wanted to know whether this was a result of increased detection because of more colonoscopy utilisation. As a result, they examined changes in colonoscopy rates, as well as colorectal cancer incidence, among adults aged 40–54, using nationally representative data.
American Cancer Society researchers, led by Dr Stacey Fedewa, determined past-year colonoscopy rates among more than 50,000 respondents ages 40-54 in the National Health Interview Survey data. Colorectal cancer incidence rates and incidence rate ratios were calculated based on 18 population-based Surveillance Epidemiology and End Results registries during the same period.
If the growing incidence of young onset CRCs were a result of more detection, larger increases in early-stage diagnoses would be anticipated because screening is most likely to detect localised disease.
Between 2000 and 2015, past-year colonoscopy rates were fairly stable among people aged 40-44 (remaining under 3%), while colorectal cancer incidence rates increased by 28%. Among those ages 45-49, colonoscopy rates doubled (from 2.5% in 2000 to 5.2% in 2015), while colorectal cancer incidence rates increased by 15%. In those ages 50-54, colonoscopy rates increased by about 2.5 times (from 5.0% to 14.1%), while incidence rates rose 17%.
"The changes in past-year colonoscopy rates did not fully align with the rise in overall and distant stage colorectal cancer incidence rates in all three age groups during the corresponding period," said Fedewa. "There were some concordant patterns, like the rise in both colonoscopy and early stage incidence among 50-54 years, but there were also some discordant patterns, such as the lack of increase in colonoscopy among people in their early 40's to match the increasing rates of CRC in this age group.”
“Future studies should examine reasons for the rising CRC incidence rates in young adults," the study concludes.