Rise in Early-Onset Colorectal Cancer Not Fully Aligned With Screening Trends
A new study finds that trends in colonoscopy rates did not fully align with recent increases in colorectal cancer incidence in younger adults. The findings were published by Fedewa et al in the Journal of Medical Screening.
Colorectal cancer incidence rates are declining in adults older than 55 years in the United States, partly because of the widespread uptake of colonoscopy. In contrast, colorectal cancer incidence in younger adults is rising. There remains debate whether the rise in incidence in younger adults reflects an actual increase in disease, or rather increased detection as a result of more colonoscopies being performed over time.
Methods
American Cancer Society researchers led by Stacey Fedewa, PhD, determined past-year colonoscopy rates among more than 50,000 respondents aged 40–54 years 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.
Results
Between 2000 and 2015, past-year colonoscopy rates were fairly stable among people aged 40–44 years (remaining under 3%), while colorectal cancer incidence rates increased by 28%. Among those aged 45–49 years, colonoscopy rates doubled (from 2.5% in 2000 to 5.2% in 2015), while colorectal cancer incidence rates increased by 15%. In those aged 50–54 years, colonoscopy rates increased by about 2.5 times (from 5.0% to 14.1%), while incidence rates rose 17%.
If the growing incidence of young-onset colorectal cancers were a result of more detection, larger increases in early-stage diagnoses would be anticipated, because screening is most likely to detect localized disease. To investigate this, researchers examined stage-specific colorectal cancer incidence trends from 2000–2015. Increases in localized disease occurred in those aged 40–44 years, among whom colonoscopy was stable, but not in those aged 45–49 years, among whom colonoscopy rates had increased. However, distant-stage disease increased in every age group, and was steeper (2.9% per year) than that for localized stage (1.1% per year) in those aged 40–44 years.
“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 Dr. Fedewa. “There were some concordant patterns, like the rise in both colonoscopy and early-stage incidence among [those aged] 50–54 years, but there were also some discordant patterns, such as the lack of increase in colonoscopy among people in their early 40s to match the increasing rates of colorectal cancer in this age group.”
Researchers concluded, “Past-year colonoscopy rates during 2000–2015 were stable among people aged 40–44 and increased among those aged 45–54, which does not fully align with the rise in overall and distant-stage colorectal cancer incidence rates in all three age groups during the corresponding period. Future studies should examine reasons for the rising colorectal cancer 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.”
Disclosure: For full disclosures of the study authors, visit journals.sagepub.com.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
