Weight Loss Trial Reports Success for Breast Cancer Patients at One Year Mark

Dana-Farber investigators find that breast cancer patients experienced notable weight loss on the Breast Cancer Weight Loss Trial (BWEL) intervention after one year compared to those receiving education only.

Boston, August 21, 2025 – Breast cancer patients who participated in a remote weight loss intervention program lost an average of 4.7 percent of their baseline body weight after one year, while those in the education only control group gained an average 1 percent of their baseline weight, according to a new report from Dana-Farber Cancer Institute investigators. The findings from the Breast Cancer Weight Loss (BWEL) clinical trial set the stage for ongoing research to determine if weight loss following breast cancer treatment can reduce the risk of cancer recurrence and extend survival.

The results were published in JAMA Oncology.

“This remotely delivered intervention was successful in helping women lose weight across many different patient and treatment factors and it worked well across a large number of sites across the U.S. and Canada,” says Dana-Farber’s Jennifer Ligibel, MD, principal investigator on the study. “These results put us in a great position to be able to determine whether the weight loss program will help reduce the risk of cancer recurrence.”

Obesity is a risk factor for recurrence of breast cancer, other related health problems, and poor quality of life. There is a strong need to find an effective and reliable way to help patients lose weight after diagnosis and treatment for breast cancer.

The Breast Cancer Weight Loss (BWEL) trial, a Phase III trial supported by the National Cancer Institute and the Susan G. Komen Foundation, enrolled nearly 3,180 women from more than 637 cancer treatment centers in the U.S. and Canada. The participants, who had been diagnosed with stage 2 or 3 HER2-negative breast cancer, had completed chemotherapy and radiation therapy (if it was to be administered) and were randomly assigned to receive either a telephone-based weight-loss program plus health education or health education alone. The weight-loss program, conducted by phone, coached patients in reducing their calorie intake and increasing exercise.

In this planned analysis of results for patients after 12-months, 46.5 percent of patients on the weight loss intervention lost 5 percent of their baseline body weight and 22.5 percent lost 10 percent. In contrast, only 14.3 percent of those in the control group lost 5 percent of baseline body weight and 5 percent of controls lost 10 percent. Further, 21.9 percent of controls gained more than 5 percent of baseline body weight compared to 8.2 percent in the weight loss intervention.

“It is very hard after being diagnosed with breast cancer to lose weight and many people gain weight,” says Ligibel. “This study really underscores that it is important to help patients with their weight after a breast cancer diagnosis.”

Patients experienced weight loss on the weight loss intervention regardless of education level, socioeconomic status, and treatment types, including patients on anti-estrogen therapies. The results did show less weight loss in premenopausal, African American, and Latina patients.

“More research is needed to fine tune weight loss interventions for different groups of breast cancer survivors,” says Ligibel.

“Every person deserves the chance to be as healthy as possible after a breast cancer diagnosis. Susan G. Komen is proud to have supported Dr. Ligibel’s pioneering BWEL trial since 2016,” says Kimberly Sabelko, Ph.D., vice president of scientific strategy and programs at Susan G. Komen. “We are so grateful to the patients who are participating in it, as the findings are poised to provide us with evidence-based behavioral interventions that could help many patients live longer, better lives. This initial report demonstrating that weight loss is achievable across a diverse patient population is very encouraging, and we look forward to the long-term results.”

The study provided the intervention in both English and Spanish and provided a toolbox of recipe recommendations to support a range of dietary preferences including vegetarian, vegan, and low-carbohydrate diets. Recipes included Caribbean, Mexican, and Indian foods. Commercial partners supported the trial by donating activity monitors, wireless scales, meal replacement shakes, and food scales for patients to use if desired.

“We tried to meet people where they were as long as they were adhering to a healthy diet, the caloric restrictions, and activity levels,” says Ligibel. “Patients need support and an infrastructure, and this study offers an intervention that works across many sites and across a wide range of people.”

The long-term goal of the BWEL study will be to determine if the intervention reduces breast cancer recurrence. If it does, the program could become something more widely available to patients.

“We are working toward insurance reimbursement for weight loss programs for patients with breast cancer, making this kind of intervention available for patients regardless of their ability to pay for it themselves,” says Ligibel.

Funding: National Institute of Health, Susan G. Komen Foundation, Breast Cancer Research Foundation, the American Cancer Society. Product support was provided by Google, Nestlé Health Sciences, Harvard University Press, and Ozeri Corporation.

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About Dana-Farber Cancer Institute

Dana-Farber Cancer Institute is one of the world’s leading centers of cancer research and treatment. Dana-Farber’s mission is to reduce the burden of cancer through scientific inquiry, clinical care, education, community engagement and advocacy. Dana-Farber is a federally designated Comprehensive Cancer Center and a teaching affiliate of Harvard Medical School.

Dana-Farber is the only hospital nationwide with a top 3 U.S. News and World Report Best Cancer Hospital ranking in both adult and pediatric care.

As aglobal leader in oncology, Dana-Farber is dedicated to a unique and equal balance between cancer research and care, translating the results of discovery into new treatments for patients locally and around the world, offeringmore than 1,100 clinical trials.

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