A telephone-based weight loss program improved physical function, overall physical and mental health, fatigue, and social role outcomes compared with health education alone in patients with stage II to III breast cancer and a body mass index (BMI) of at least 27, according to substudy findings from the phase 3 BWEL trial (NCT02750826) shared during 2026 American Society of Clinical Oncology (ASCO) Annual Meeting press briefing.1
Additional details will be presented during the Annual Meeting from May 29 to June 2 in Chicago, Illinois. CancerNetwork® will continue to provide coverage of the BWEL trial findings and additional patient-reported outcome data during the presentation next week.
At 6 months, patients in the weight loss intervention arm had a 1.9-point higher mean improvement in physical function and a 2.0-point higher improvement in overall physical health vs the health education arm. Mental health scores were 1.3 points higher in the intervention arm. Patient-reported fatigue scores were 1.7 points lower, and social role and activity scores—including ability to work and socialize—were 2.3 points higher with the intervention. Researchers reported that improvements were generally maintained at 2 years after enrollment.
The Patient-Reported Outcomes Measurement Information System (PROMIS) was used to assess physical, mental, and social health at enrollment, 6 months, and 2 years. PROMIS uses a scale where 50 represents the average for the US general population.
“The BWEL program was delivered to more than 1500 participants enrolled from across 635 oncology practices in the [US] and Canada,” lead author Jennifer A. Ligibel, MD, director of the Leonard P. Zakim Center for Integrative Therapies and Healthy Living at the Dana-Farber Cancer Institute in Boston, Massachusetts, said in the press release. “These findings thus show not only that weight loss provides meaningful benefits for people who have both breast cancer and obesity, but also that this can be achieved in thousands of patients enrolled across many kinds of oncology practices.” Ligibel previously discussed the broader role of weight loss in cancer risk in a recent CancerNetwork interview.
BWEL Trial Design
The BWEL trial randomly assigned 542 participants with stage II to III breast cancer and a BMI of at least 27 to either a telephone-based weight loss program plus health education (n = 272) or to health education alone (n = 270). The intervention was a 2-year program in which participants were paired with a coach who delivered up to 42 telephone-based behavioral counseling sessions designed to reduce caloric intake and increase physical activity to support diet, exercise, and weight loss goals. The control arm received only health education, which included materials on diet and physical activity.
Previously reported BWEL findings demonstrated that the telephone-based intervention produced clinically meaningful weight loss in patients with breast cancer who were overweight or obese. The current substudy aimed to evaluate whether weight loss in this setting also drives improvements in patient-reported physical function and quality of life.
PROs were collected at study enrollment, 6 months, and 2 years using PROMIS instruments measuring physical function, overall physical health, overall mental health, fatigue, and ability to participate in social roles and activities.
ASCO Perspective and Clinical Context
“We’ve asked patients with stage II to III breast cancer who are overweight or obese to lose weight for years without offering them much of a structured program. BWEL changes that conversation not just because of the survival data, but also because patients in the intervention arm felt measurably better in their physical function, fatigue, and social engagement,” said Marcin Chwistek, MD, FAAHPM, chief of Supportive Oncology and Palliative Care Program at Fox Chase Cancer Center and an ASCO Expert in supportive care, in the press release. “A program that improves survival and quality of life simultaneously is a program worth delivering.”
Next Steps and Coverage Plans
The investigators plan to evaluate whether baseline physical function and quality of life predict the success of the weight loss intervention, with the goal of identifying patients most likely to benefit. Researchers are also planning to examine whether the magnitude of weight loss itself—rather than coaching participation alone—drives the observed improvements in patient-reported outcomes.
Follow CancerNetwork® for full data readout coverage of the BWEL trial during the 2026 ASCO Annual Meeting, including detailed PRO outcomes, subgroup analyses, and accompanying expert commentary from the presentation.
References
Weight loss program improves physical function, quality of life for patients with breast cancer. News release. American Society of Clinical Oncology. May 21, 2026. Accessed May 21, 2026.
