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. 2020 Oct 15;126(20):4553-4562.
doi: 10.1002/cncr.33050. Epub 2020 Aug 8.

Emerging cancer incidence trends in Canada: The growing burden of young adult cancers

Emily V Heer  1 , Andrew S Harper  1 , Hyuna Sung  2 , Ahmedin Jemal  2 , Miranda M Fidler-Benaoudia  1   3   4
Affiliations
Free article

Emerging cancer incidence trends in Canada: The growing burden of young adult cancers

Emily V Heer et al. Cancer. .
Free article

Abstract

Background: Recent studies have identified increases in cancer incidence among younger adults for some cancers. This study examined incidence trends for 28 cancers in Canada by age and birth cohort from 1983 to 2012.

Methods: Canadian incidence data for 20 to 84 year-olds were obtained from the Cancer Incidence in Five Continents Plus database. Age-period-cohort modeling was used to estimate the average annual percentage changes (AAPCs) and incidence rate ratios (IRRs) for 10-year birth cohorts (reference cohort, 1943) for 28 cancer types.

Results: Incidence increased for 13 cancer sites among adults younger than 50 years (1983-2012), with the largest increase occurring for rectal cancer (AAPC20-24 , 5.62; 95% confidence interval [CI], 3.77-7.51) and colon cancer (AAPC20-24 , 4.08; 95% CI, 2.89-5.29). Compared with the 1943 birth cohort, persons born circa 1988 had approximately 5- and 2-fold greater risks of rectal cancer (IRR, 4.98; 95% CI, 2.87-8.63) and colon cancer (IRR, 2.31; 95% CI, 1.62-3.30), respectively. Incidence decreased among younger adults for 9 sites (1983-2012), with the largest decreases observed for lung cancer (AAPC25-29 ,-2.29; 95% CI, -3.57 to -0.98), cervical cancer (AAPC25-29 , -1.29; 95% CI, -1.67 to -0.90), and melanoma (AAPC25-29 , -0.61; 95% CI, -0.97 to -0.24). Decreased risks in recent birth cohorts were observed for all sites with decreasing trends in younger adults. For example, the risk of lung cancer was 60% lower in the 1988 birth cohort than the 1943 birth cohort (IRR, 0.42; 95% CI, 0.23-0.78).

Conclusions: Incidence among young adults is increasing for some cancers associated with obesity but decreasing for many cancers associated with infections or smoking. Although further studies are needed to replicate these findings and understand the etiology of early-onset cancers, measures to promote healthy behaviors in young adults warranted.

Keywords: Canada; cancer prevention; epidemiology; incidence; young adult cancer.

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References

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    1. Brenner DR, Heer E, Sutherland RL, et al. National trends in colorectal cancer incidence among older and younger adults in Canada. JAMA Netw Open. 2019;2:e198090.
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    1. Khan SA, Morris M, Idrees K, et al. Colorectal cancer in the very young: a comparative study of tumor markers, pathology and survival in early onset and adult onset patients. J Pediatr Surg. 2016;51:1812-1817.

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