BWEL: a phone-based weight loss intervention in early-stage breast cancer

Initial data from the Phase III Breast Cancer Weight Loss Study (BWEL) (NCT02750826) has shown promising results for a telephone-based weight loss intervention program (WLI) in overweight and obese patients with early-stage breast cancer.1,2 The research was presented at this year’s 2023 annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago, IL.

Obesity is a factor linked with poor prognosis for patients with breast cancer. It is defined as a body mass index (BMI) of 30kg/m2 or more, which affects more than one billion individuals globally.3 Obesity can present multiple challenges to patients with breast cancer, such as an increased risk of developing diabetes, cardiovascular disease, and mortality.3 Women with obesity and breast cancer have a 41% increased risk of all-cause mortality and a 60% increased risk of cardiovascular disease-related mortality; the latter is one of the main causes of mortality in women with early-stage breast cancer.3,4 Obesity can also affect the dosage of chemotherapy; in 2021, ASCO updated their guidelines for appropriate dosing in adults with cancer and obesity.5

To address the poor disease-free and overall-survival, the BWEL trial aims to evaluate the impact of a telephone-based WLI on invasive disease-free survival (IDFS) in female patients with a BMI in the overweight range (BMI:27-29.9kg/m2) and obese range (BMI: ≥30kg/m2), diagnosed with stage II-III HER2-negative breast cancer. 1,2 Between 2016 and 2021, female patients were enrolled (n=3181) at more than 600 sites in the U.S and Canada. This was the first Phase III study designed to specifically assess whether a WLI program could reduce cancer recurrence and mortality in patients who are obese through caloric restriction and exercise. 2 Patients were randomized 1:1 to the telephone-based WLI plus health education (HE) arm or to the control group with HE alone. The HE program consisted of evidence-based materials supporting a healthy lifestyle [5]. Statistical analysis was performed which factored in baseline weight, menopausal status, race/ethnicity, and hormone receptor (HR) status.

Among the cohort, the baseline mean BMI was 34.5 kg/m2 with an average age of 53.4 years. The telephone-based WLI led to a significant decrease in weight relative to the control group (4.8% vs 0.8%) across the tumor factors and patient demographic (80.3% White, 12.8% Black, 7.3% Hispanic) at the 12-month follow-up. 1,2 While weight loss did not differ by HR status (interaction p-value= 0.17), it did vary significantly by race/ethnicity (interaction p value=0.019) and by menopausal status (interaction p value= 0.0057, 57% patients).

According to the lead author, Jennifer Ligibel, MD, from the Dana-Farber Cancer Institute in Boston, MA, the “study provides compelling evidence that weight loss interventions can successfully reduce weight in a diverse population of patients with breast cancer”. 2

There have been two previous WLI trials studying the effects of dietary intervention after diagnosis (WINS and WHEL studies).6,7 Both have conflicting results and do not evaluate the impact of physical activity. This telephone-based WLI demonstrates a cost-effective and accessible approach to induce clinically significant weight loss in patients with breast cancer who are obese or overweight. 2 41.9% of the population in the United States is obese, and the incidence of breast cancer is increasing by 0.5%.3 Postmenopausal women with obesity are more likely to present with an aggressive and advanced disease at diagnosis.3

This WLI could help establish important behavioral changes in patients with obesity and breast cancer. With additional tailoring, the WLI may be useful to enhance weight loss in certain demographics and younger patients. 1,2 Patient compliance will be vital in the effort to maintain lifestyle changes; generally, overweight women have poorer compliance with healthy habits.4 A follow-up of the BWEL trial will evaluate whether WLI improves disease outcomes. 1,2

Written by Lemuel Fulgencio

Edited by Ellie Jackson


  1. Ligibel JA, Ballman KV, McCall LM, et al. Effect of a telephone-based weight loss intervention (WLI) on weight at 12-months in women with early breast cancer: Results from the breast cancer weight loss (BWEL) trial. Journal of Clinical Oncology. 2023;41(16_suppl):12001–12001. doi:10.1200/jco.2023.41.16_suppl.12001
  2. Telephone-based coaching intervention leads to weight loss in patients with breast cancer. 2023. Available from:
  3. LeVee A, Mortimer J. The challenges of treating patients with breast cancer and obesity. Cancers. 2023; 15(9): 2526
  4. Lee K, Kruper L, Dieli-Conwright C.M, et al. The impact of obesity on breast cancer diagnosis and treatment. Current Oncology Reports. 2019; 21(41)
  5. Griggs J.J, Bohlke K, Balaban E.P, et al. Appropriate systemic therapy dosing for obese adult patients with cancer: ASCO guideline update. Journal of Clinical Oncology. 2021; 39(18): 2037-48
  6. Gauging the impact of weight loss intervention on breast cancer outcomes. The ASCO Post. Available from:
  7. Ligibel J.A, Basen-Engquist K, Bea J.W. Weight management and physical activity for breast cancer prevention and control. ASCO Educational Book. 2019; 3: e22-e33