You might want to add diet and exercise to your New Year's resolution, as a study published last week in JAMA Oncology found more than 7% of cancer cases among U.S. adults were associated with excess body weight.
The researchers set out to calculate the portion of cancer cases in all 50 states and Washington, D.C., that are attributable to excess body weight, which the researchers wrote is "an established cause of cancer."
The researchers used data from the Behavioral Risk Factor Surveillance System to collect state-level, self-reported body mass indexes (BMIs) of adults who were ages 30 and older in 2011 to 2015. The researchers also collected state-level cancer incidence data from the U.S. Cancer Statistics database for all 50 states.
After adjusting participants' BMI data by race/ethnicity, age, and sex, the researchers honed in on four "high BMI categories" to estimate the portion of cancer cases in each state between 2011 and 2015 that were attributable to excess weight. The findings are estimations, because they are based on risk-adjusted calculations and assumptions, not incidence-based data.
Researchers find excess weight was linked to cancer, particularly among women
The researchers estimated that, from 2011 to 2015, 4.7% of cancer cases in U.S. men and 9.6% of cancer cases in U.S. women were attributable to excess weight.
The population attributable fraction (PAF) of cancer cases caused by excess weight for women ranged from 7.1% in Hawaii to 11.4% in Washington, D.C. The PAF among women was approximately two times higher than the PAF among men, which ranged from 3.9% in Montana to 6% in Texas, the researchers found.
Southern and Midwestern states, as well as Alaska and Washington, D.C., had the highest rates of weight-attributable cancers across both men and women, at 8% or higher. In comparison, New England, Mountain states, and Hawaii had the lowest rates, at 6% or less, according to the researchers.
While the PAF varied by a 1.5-fold change between states, at least one in 17 cancer cases across all 50 states and Washington, D.C., were attributable to excess weight, the researchers estimated.
How the obesity epidemic plays a role
Previous research confirmed that excess body fat increases individuals' risk for at least 12 cancers, the Times reports. According to the Times, people with excess body fat are at highest risk of developing liver, esophageal, and uterine cancers.
As the obesity epidemic worsens in the United States, the portion of weight-attributable cancer cases may increase, according to Farhad Islami, lead author of the study and scientific director at the American Cancer Society.
The study authors concluded that in order to prevent an increase in weight-attributable cancers, "broad implementation of known community- and individual-level interventions is needed" to decrease the incidence of obesity in the United States. Such interventions ideally would "reduce access to and marketing of unhealthy foods … and to promote and increase access to healthy foods and physical activity, as well as preventive care," the researchers wrote.
Islami said, "A range of interventions could be useful," such as, "[z]oning and licensing to encourage more fresh food outlets, taxes on sugary beverages, [and] interventions at school and in the workplace." He added, "It's important to have authorities at the state and local level implement some interventions to lower body weight" (Bakalar, New York Times, 1/2; Islami et al., JAMA Oncology, 12/27/2018).
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