Rising cancer incidence in younger adults: is obesity to blame?
Menée à partir des données de 25 registres américains des cancers portant sur 14 672 409 patients atteints de 30 types de cancers, dont 12 liés à l'obésité, cette étude analyse, en fonction de la tranche d'âge (de 25-29 ans à 80-84 ans, par tranche d'âge de 5 ans), l'évolution du risque de cancer sur la période 1995-2014
Although cancer has historically been considered a disease of aging, a reported sharp rise in colorectal cancer incidence among adults aged 54 years and younger beginning in the mid-1980s for the colon and mid-1970s for the rectum has motivated researchers to examine risk factors for early onset disease. InThe Lancet Public Health, Hyuna Sung and colleagues report a rigorous and extensive analysis of data from 25 state cancer registries, in which they examined contemporary incidence trends for 30 cancers in the USA. This analysis, which included 14 672 409 incident cancers ascertained from registries covering 67% of the US population between Jan 1, 1995, and Dec 31, 2014, extends their previous work on colorectal cancer incidence. The new study included 12 cancers considered to be related to obesity according to a 2016 report from a working group convened by the International Agency for Research on Cancer, and 18 additional common cancers not designated as obesity-related in the same report. The investigators examined trends in incidence, based on annual percentage changes and incidence rate ratios, for each of the 30 cancer types by age and birth cohort.
The most striking finding was that cancer incidence appears to be rising disproportionately in younger adults (aged 25–49 years), and in consecutively younger birth cohorts for half of the cancers classified as obesity-related. These cancers include colorectal, corpus uteri, gallbladder, kidney, pancreatic, and multiple myeloma. Thyroid cancer, also considered to be obesity-related, showed markedly rising incidence in both younger and older adults. By contrast, only two of the other 18 cancers had similar trends of increasing incidence in younger adults. The investigators speculate that these findings are driven in part by the obesity epidemic, a hypothesis that is both provocative and plausible. As the investigators state, the prevalence of obesity in the USA more than doubled between 1980 and 2014,5
providing compelling evidence that obesity could be a causal factor. However, despite the plausibility, the investigators' hypothesis and report have constraints that are important to consider. (...)
The Lancet Public Health , commentaire, 2018