The incidence of obesity-related cancers has sharply increased among adolescent and young adult (AYA) patients, though smoking-related cancers have decreased, according to a study published in JNCI Journal of the National Cancer Institute.

AYA cancers are recognized as a unique spectrum of malignancies, yet most epidemiological studies stratify this population in with children or adults. As a result, there is a lack of knowledge about the characteristics of AYA cancers. The purpose of this study was to characterize the incidence of cancer in this population.

The study included 1,846,588 new AYA cancer cases diagnosed between 1998 and 2012 from 41 countries obtained from the International Agency for Research on Cancer’s CI5plus database. AYA cancers were defined as those diagnosed among individuals aged 15 to 39 years.

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Overall cancer incidences varied with countries, as some demonstrated a trend of increasing incidence, while 2 countries showed a downward trend and 16 had plateaued. The incidences of obesity-related cancers were increasing, including cancers of the uterus, pancreas, gallbladder, and liver in some countries. Smoking related-cancers decreased, with the incidence of lung cancer decreasing.

There were more specific trends observed. For example, the incidence of thyroid cancer increased in 33 countries. For colon cancer, the incidence was stable in 24 countries, but increasing in 17, including among white Americans and in the United Kingdom.

The incidence of breast cancer as stable in 21 countries, but rising in 19 countries, including those located within Western and Eastern Europe and Asia. The incidence of testicular cancer increased in 22 countries.

The authors concluded, “our results have demonstrated unique trends in the incidence of AYA cancer.” They added that “these data advocate for prevention and screening strategies that are of the most relevance in the represented AYA population and indicate future health-care needs.”


Gupta S, Harper A, Ruan Y, et al. International trends in the incidence of cancer among adolescents and young adults. JNCI J Natl Cancer Inst. 2020;112:djaa007. doi:10.1093/jnci/djaa007