Study: Intensive Lifestyle Intervention Focused on Weight Loss Lowers Obesity-Related Cancer Risk

A study from The Obesity Society found that an intensive lifestyle intervention (ILI) aimed at weight loss lowered incidence of obesity-related cancers in adults with overweight or obesity and type 2 diabetes (T2D). It is the only randomized clinical trial that has examined long-term cancer outcomes in an ILI focused on weight loss, according to the study authors.

Previous studies have shown how obesity is associated with an increased risk of some cancers, but there was no evidence from clinical trials to date that have evaluated whether ILI for weight loss can reduce the risk of cancer.

Using data from the Look Action for Health in Diabetes (AHEAD) trial, researchers investigated whether participants randomized to the ILI designed for weight loss would have reduced overall cancer incidence, obesity-related cancer incidence, and cancer mortality compared with a diabetes support and education (DSE) group.

To further evaluate the cancer outcomes, 4859 participants who had not reported a cancer diagnosis at baseline were included. Participants had to be between 45 and 76 years of age, have a body mass index greater than 25, glycated hemoglobin less than 11%, blood pressure readings less than 160/100 mm Hg, triglyceride levels less than 600 mg/dL, and completion of a maximal graded exercise test, according to the study authors.

Participants were randomly assigned to an ILI or a DSE by a web-based data management system between August 22, 2001, and April 30, 2004, at Wake Forest School of Medicine in Winston-Salem, North Carolina.

The ILI was designed to achieve and maintain weight loss of at least 7% by facilitating reduced caloric intake and increased physical activity. These specific intervention strategies included a calorie goal of 1200 to 1800 kcal/d, the use of meal replacement products, and at least 175 minutes of moderate-intensity physical activity per week.

In the DSE comparison group, diabetes support and education were provided through 3 group sessions per year on diet, exercise, and social support during years 1 through 4. In subsequent years, the frequency was reduced to 1 session annually, according to the study authors.

After an average follow-up of 11 years, 684 participants were diagnosed with cancer. Incidence rates of obesity-related cancers were 6.1 and 7.3 per 1000 person-years in ILI and DSE with a hazard ratio of 0.84. There was no significant difference found between the 2 groups in total cancer incidence, incidence of non-obesity related cancers, or total cancer mortality.

The researchers found that an ILI aimed at weight loss lowered incidence of obesity-related cancers by 16% in adults with overweight or obesity and T2D. They noted the sample size likely lacked power to determine effect sizes of this magnitude and smaller.

"While underpowered to detect significant differences, this analysis of Look AHEAD data is an important contribution, as it is one of the first studies to provide empirical data to suggest that a weight loss-focused lifestyle intervention can help to lower risk of obesity-related cancers," said Tiffany L. Carson, PhD, MPH, assistant professor, Division of Preventive Medicine, Department of Medicine, University of Alabama at Birmingham, in a press release.

Carson added that in addition to having adequate sample sizes to test for effects, which will likely require pooled data, future studies should also explore the magnitude of weight loss that is needed to lower the risk for obesity-associated cancers.

REFERENCE

Intensive lifestyle intervention focused on weight loss lowers obesity-related cancer risk. EurekAlert! https://www.eurekalert.org/pub_releases/2020-08/tos-ili081820.php. Published August 24, 2020. Accessed August 24, 2020.