Elsevier

Preventive Medicine

Volume 105, December 2017, Pages 345-349
Preventive Medicine

Increasing colorectal cancer incidence trends among younger adults in Canada

https://doi.org/10.1016/j.ypmed.2017.10.007Get rights and content
Under a Creative Commons license
open access

Highlights

  • Colorectal cancer incidence in Canada is decreasing in older populations.

  • However, there is a significant increase in incidence in adults under 50 years old.

  • Increasing incidence in younger adults may be associated with increasing obesity.

Abstract

Recent analyses in the United States have shown an overall decrease in the incidence of colorectal cancer despite contrasting increases in younger age groups. We examined whether these cohort trends are occurring in Canada. Age-specific trends in colon and rectal cancer incidence in Canada from the National Cancer Incidence Reporting System (1969–1992) and the Canadian Cancer Registry (1992–2012) were analyzed. We estimated annual percent changes (APC) with the Joinpoint Regression Program from the Surveillance Epidemiology, and End Results Program. Birth cohort effects were estimated using 5-year groups starting in 1888. Age-specific prevalence of class I, II and III obesity in Canada was examined from the National Population Health Survey (1994–2001) and the Canadian Community Health Survey (2001–2011). The reductions in CRC incidence among Canadians are limited to older populations. While reductions among younger age groups (20–29 year olds (yo), 30–39 yo and 40–50 yo) were observed between 1969 and 1995, rates have returned to and surpassed historical levels (APCs 20–29 yo colon cancer = 6.24%, APCs 20–29 yo rectal cancer = 1.5%). Recent birth cohorts (1970–1990) have the highest incidence rate ratios ever recorded. Ecologic trends in obesity prevalence among these birth cohorts in Canada are suggestive of an impact on increasing incidence trends. Furthermore, obesity prevalence estimates suggest that these trends may continue to increase justifying further examination of the etiologic associations and biological impacts of excess adipose tissue among younger populations. While population-based screening of younger age groups deserves careful consideration, these concerning observed trends warrant public health action to address the growing obesity epidemic.

Keywords

Colorectal cancer
Incidence
Age-specific trends
Obesity

Abbreviations

CRC
Colorectal cancer
APC
Annual percent change
yo
Year old
IRR
Incidence rate ratio
ITS
Interrupted time series

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