Obesity-Related Cancers Are on the Rise in Young Adults

Monitoring cancer trends in adults under age 50 can help shed light on carcinogenic exposures that foreshadow the future burden of disease in older adults, and a recent observational study, which used data covering more than half of the US population, found that the incidence of cancer linked to obesity is on the rise in young adults.

The researchers, who received funding from the American Cancer Society and the National Cancer Institute, gleaned data from the Cancer in North America database of the North American Association of Central Cancer Registries to assess information on invasive cases of cancer diagnosed in patients aged 25 to 84 years between 1995 and 2014. They focused on 12 cancer types that the International Agency for Research on Cancer has found to be associated with obesity: colorectal, esophageal, gallbladder, gastric cardia, kidney, liver and intrahepatic bile duct, multiple myeloma, pancreatic, and thyroid cancer, and, in women, uterine corpus, breast, and ovarian cancer.

During the study period, the incidences of multiple myeloma and cancers of the colorectum, corpus uteri, gallbladder, kidney, pancreas, and thyroid all increased in younger adults (those aged 25 to 49 years), and the magnitude of the increases grew steeper with younger age for all of these cancers with the exception of thyroid cancer.

The age-specific incidence of the same obesity-related cancer increased for adults aged over 50 as well, with the exception of colorectal and uterine corpus cancer. However, the magnitudes of the increases in older adults were smaller than they were in younger adults.

These trends, write the authors, may be influenced by the rise in overweight or obesity prevalence in the United States; between 1980 and 2014, overweight or obesity prevalence increased from 14.7% to 33.4% among children and adolescents, and from 48.5 to 78.2% among adults aged 20 to 74. While the effect of excess body weight in early life has not been well characterized in the literature, growing evidence suggests an association between childhood or adolescent obesity and increased cancer risk, and adult weight gain is also associated with increased risk.

Furthermore, as lead author Hyuna Sung, PhD, of the American Cancer Society, explained in a statement, obesity is also associated with health conditions that can contribute to the risk of cancer. “For example, diabetes, gallstones, inflammatory bowel disease, and poor diet can all increase the burden of cancer,” said Sung. “The quality of the American diet also has worsened in recent decades. More than half of adults who were 20 to 49 years old between 2010 to 2012 reported poor dietary habits, such as eating little fruits, vegetables, whole grains, fish and shellfish at the same time as eating too much salt, fast food, and sugary drinks.”

The authors say that their findings have significant implications for healthcare providers and policy makers. While national guidelines recommend screening children and adults for obesity and providing appropriate interventions, fewer than half of primary care physicians regularly assess the body mass index of their patients, and only one-third of patients with obesity report having received a diagnosis or counseling. Similarly, community-level interventions—like promoting physical activity or taxing sugary beverages—have yet to be broadly adopted.

The need to address these issues, say the authors, is urgent: “The future burden of these cancers might be exacerbated as younger cohorts age, potentially halting or reversing the progress achieved in reducing cancer mortality over the past several decades.”

Reference

Sung H, Siegel RL, Rosenberg PS, Jemal A. Emerging cancer trends among young adults in the USA: analysis of a population-based cancer registry [published online February 4, 2019]. Lancet Public Health. doi: 10.1016/ S2468-2667(18)30267-6.