Obesity More Prevalent in Survivors, Others With a History of Cancer

Survivors of cancer have higher prevalence of obesity than the general population, according to a large, population-based study that suggests an area to focus on as the number of cancer survivors continues to grow in the U.S.

For their study, researchers at Colombia University’s Mailman School of Public Health analyzed data from a nationally representative sample of 538,969 adults aged 18-85 years who self-reported their height and weight as part of the ongoing National Health Interview Survey (NHIS) during the time period 1997-2014; 32,447 of the participants were cancer survivors.

Researchers found a consistently increasing burden of obesity (defined as 30 kg/m2 or more for non-Asian participants and more than 27 kg/m2 for Asians) among men and women with a history of cancer when compared with adults without a history of cancer. Adult cancer survivors had an increase in obesity prevalence from 22.4 percent in 1997 to 31.7 percent in 2014, compared with 20.9 percent to 29.5 percent over that same timespan in adults without a history of cancer.

This increase was more pronounced in female survivors overall, in breast and colorectal cancer survivors, and among non-Hispanic blacks. “The prevalence of obesity grew more rapidly in in nearly every subgroup of colorectal and breast cancer survivors, compared with the corresponding groups of adults without a history of cancer,” the authors wrote.

Additionally, the occurrence of class 1 obesity (BMI: 30 to 35 kg/m2) increased in women who were cancer survivors from 13.6 percent in 1997 to 21.0 percent in 2014 exceeding that of non-survivors (12.2 percent to 16.6 percent). This trend held true across all time periods, with differences expanding over time, the authors noted.

Principal investigator Heather Greenlee, N.D., Ph.D., assistant professor of Epidemiology at the Mailman School, explained in a statement that the populations identified “are important populations in which oncology care providers should focus weight management efforts.”

Study authors also noted that specific cancer treatments, including chemotherapy, steroid medications and hormonal therapy, can play a role in weight gain for survivors.

It is also important, they cautioned, to consider obesity among cancer survivors not only in relation to cancer outcomes, but also in relation to other comorbid diseases. Obesity can cause additional health hazards for cancer survivors, as it can influence other medical conditions such as diabetes, heart disease, hypertension and hypercholesterolemia, which could affect overall survival. Studies of breast, colon and prostate cancer have shown that comorbid conditions increase five-year all-cause and cancer-specific mortality.

The researchers on this NHIS analysis predicted that based on their findings, the U.S. obesity burden will continue to trend upward, which will not only “increase the number of obesity-related cancers, but also result in an increased burden of obesity among cancer survivors.” Greenlee said that these results “suggest that obesity is a growing public health burden for cancer survivors, which requires targeted interventions including weight management efforts to stave off the increasing obesity trends we are seeing in cancer survivors.”

She added that although “the findings can be partially explained by the growing population of patients with breast and colorectal cancer — the two cancers most closely associated with obesity — we identified additional populations of cancer survivors at risk of obesity not as well understand and which require further study.”