Increased adult body mass index (BMI) before age 50 years is more strongly associated with risk of developing pancreatic cancer than increased BMI at older ages, according to results from a prospective cohort study presented at the American Association for Cancer Research (AACR) 2019 Annual Meeting in Atlanta, Georgia.

Although rates of smoking, a known risk factor for developing cancer, have steadily declined since the early 2000s, rates of pancreatic cancer have consistently increased in the same time period. Increased rates of pancreatic cancer may not be explained by increasing BMI as previous epidemiologic studies assessing BMI and pancreatic cancer indicate a weak association. A majority of these studies, however, assessed BMI in older adults, whereas higher BMIs in earlier adult life might more strongly associate with changing rates of pancreatic cancer.

This study used the Cancer Prevention Study II (CPS-II), which is a national assessment of cancer mortality in patients enrolled in 1982 and followed through 2014. Researchers calculated BMI from height and weight reported at enrollment in 963,317 adults who were aged 30 to 89 years at enrollment.

Of all participants in CPS-II, 8354 died from pancreatic cancer during the follow-up. Researchers determined hazard ratios (HRs) decreased with increasing age at BMI assessment.  For participants aged 30 to 49 years, the HR per 5 BMI units was 1.25 (95% confidence interval [CI], 1.18-1.33); for ages 50 to 59 years, the HR per 5 BMI units was 1.19 (95% CI, 1.14-1.23); and for ages 60 to 69 years, the HR per 5 BMI units was 1.14 (95% CI, 1.08-1.21). By the time participants were aged 70 to 89 years, the HR per 5 BMI units was just 1.13 (95% CI, 1.02-1.26). The trend was significant (P =.005).

In more recent birth cohorts (ie, younger generations), the prevalence of obesity in early middle age is higher than in older generations. With an HR of 1.25 per 5 BMI units for a 45-year-old adult, an estimated 28% of deaths due to pancreatic cancer in the United States in people born between 1970 and 1974 are attributable to BMI levels higher than 25 kg/m2. This is nearly 2 times the equivalent percentage to people born in the 1930s.

Researchers emphasized the importance of preventing excessive weight gain in younger adults as a means of decreasing the risk of developing pancreatic cancer.

Reference

Jacobs EJ, Newton CC, Patel AV, et al. The association between body mass index (BMI) and risk of pancreatic cancer depends on age at BMI assessment. Poster presented at: American Association for Cancer Research 2019 Annual Meeting; March 29-April 3, 2019; Atlanta, GA. Abstract 3281/28.