Younger adults in the United States are increasingly becoming victimized for 6 out of 12 obesity-related cancers, with higher rates in younger ages and successfully younger generations. The study published in The Lancet also found two of the 18 non-obesity related cancers were also on the rise.
The obesity epidemic over the past 40 years has led to younger generations experiencing an earlier and longer lasting exposure to excess adiposity over their lifetime than previous generations. Excess body weight is a known carcinogen, associated with more than a dozen cancers and suspected in several more. Exposures to carcinogens during early life may have an even more important influence on cancer risk by acting during crucial developmental periods.
Several years ago, the authors of the current study identified increases in early onset colorectal cancer in the U.S., a trend that has been observed in several high-income countries and could partly reflect the obesity epidemic. They extended that analysis by examining recent age-specific trends in 30 types of cancers, including 12 known to be associated with obesity.
Incidence increased for 6 of the 12 obesity-related cancers (colorectal, uterine corpus [endometrial], gallbladder, kidney, multiple myeloma, and pancreas) in young adults and in successively younger birth cohorts in a stepwise manner. For example, the risk of colorectal, uterine corpus [endometrial], pancreas, and gall bladder cancers in millennials is about double the rate baby boomers had at the same age. In contrast, rates in successive younger birth cohorts declined or stabilized in all but 2 of 18 other, non-obesity related cancers, including smoking-related and infection-related cancers.
"Although the absolute risk of these cancers is small in younger adults, these findings have important public health implications," said Ahmedin Jemal, DVM Ph.D., scientific vice president of surveillance & health services research and senior/corresponding author of the paper. "Given the large increase in the prevalence of overweight and obesity among young people and increasing risks of obesity-related cancers in contemporary birth cohorts, the future burden of these cancers could worsen as younger cohorts age, potentially halting or reversing the progress achieved in reducing cancer mortality over the past several decades. Cancer trends in young adults often serve as a sentinel for the future disease burden in older adults, among whom most cancer occurs."
The authors say innovative strategies are needed to mitigate morbidity and premature mortality associated with obesity-related diseases, primarily by health-care providers and policy makers.