Irwin, M.

Abstract BACKGROUND: Obesity is prevalent in Hispanic patients (pts) with breast cancer (BC), but this population is often underrepresented in studies of weight loss interventions (WLIs). The BWEL trial (Alliance A011401; NCT02750826) is a phase III randomized trial testing the impact of a 2-year (yr) telephone-based WLI on invasive disease-free survival in pts with stage II-III HER2-negative BC and a body mass index (BMI) > 27 kg/m2. At 12 months (mo), Hispanic pts lost less weight than White pts on the WLI. Here, we evaluate differences in intervention engagement over the first 12 mo by language preference and ethnicity among BWEL pts on the WLI. METHODS: BWEL randomized pts 1:1 to WLI + health education (HE) or HE alone. WLI +HE pts received semi-structured telephone-based health coaching in English or Spanish, in addition to access to an activity monitor, wireless scale and meal replacement shakes. Pts self-reported ethnicity and their preferred language for the WLI. Kruskal Wallis and chi-square tests were used to assess language and ethnicity differences in demographic and treatment factors for continuous and categorical variables, respectively. Percent weight change and mean values for intervention attrition, number of calls, call duration, number of shake shipments, and frequency of activity monitor use and weight tracking over 12 mo were compared between Spanish-preferred Hispanic pts (SH), English-preferred Hispanic (EH) pts and non-Hispanic (NH) pts using ANOVA. Pts with missing language, ethnicity or 12 mo weight data were excluded from analysis. RESULTS: 1591 pts were randomized to the WLI + HE from 08/2018 to 02/2021. 80.5% of pts were White, 12.8% Black and 7.1% Hispanic. 1190 pts had 12 mo weight and language available. Among the 87 WLI + HE pts who had available data and identified as Hispanic, 34% were SH and 66% EH. SH WLI pts were younger (in yrs: 49.5 SH, 51.1 EH, 53.9 NH, p=0.006) and had lower BMI (32.2 SH, 35.1 EH, 34.5 NH, p=0.007). At 12 mo, SH WLI pts lost 2.4% of baseline body weight vs 3.3% in EH and 5.1% in NH (p=0.051) (Table). Compared with EH and NH WLI pts, SH WLI pts participated in fewer calls (15.7 SH, 21.1 EH, 24.3 NH, p< 0.0001), had fewer days of activity monitor use (134.2 SH, 177.3 EH, 205.3 NH, p=0.015) and fewer days of weight tracking (65.3 SH, 96.8 EH, 148.2 NH, p<0.0001), but had more shake shipments (3.9 SH, 3.5 EH, 3.0 NH, p=0.015). There were no significant differences in attrition rate or call duration by language preference or ethnicity. CONCLUSIONS: In a large phase III WLI study in breast cancer patients, engagement with the WLI appeared lower in SH pts, despite provision of the intervention in Spanish. More work is needed to improve accessibility and efficacy of WLI studies among non-English speaking populations. Support: U10CA180821, U10CA180882, UG1CA189823; https://acknowledgments.alliancefound.org. Citation Format: A. Odai-Afotey, K. V. Ballman, L. M. McCall, C. Cao, C. Alfano, V. Bernstein, T. E. Crane, L. M. Delahanty, L. Frank, P. J. Goodwin, O. Hahn, D. L. Hershman, J. O. Hopkins, M. Irwin, E. L. Mayer, L. Minasian, L. Nebeling, M. Neuhouser, E. D. Paskett, P. A. Spears, V. Stearns, C. A. Thomson, T. A. Wadden, A. Weiss, J. White, C. Hudis, E. P. Winer, L. Carey, A. H. Partridge, J. Ligibel. Variation in weight loss and intervention engagement in the Breast Cancer Weight Loss (BWEL) trial by language and ethnicity (Alliance) [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS4-09-29.

Abstract Background: Obesity is a poor prognostic factor in early breast cancer (BC). The BWEL trial (Alliance A011401; NCT02750826) is a phase 3 randomized trial testing the impact of a weight loss intervention (WLI) on invasive disease-free survival in women with stage II-III BC and a body mass index (BMI) ≥27 kg/m2. Here we report trajectories of weight change in BWEL WLI participants (pts). Methods: Eligible pts were within 16 months of diagnosis of stage II-III HER2-negative BC, had completed chemotherapy (chemo) and radiation (if given), and were randomized 1:1 to a telephone-based WLI, focused on caloric restriction and exercise, plus health education (HE) or to an HE-alone control group. WLI pts were assigned a trained coach at the BWEL call center and received 42 phone calls over the 2-year (yr) WLI period. Weight and height at baseline, 6 and 24 months were collected by study staff. All WLI pts were provided with a Fitbit wireless scale. Fitbit weight records (FWRs) were automatically imported to the BWEL portal for pts with wireless access and self-reported in the portal for pts without wireless access. FWRs were averaged (avg) by week (wk) from the WLI start date up to 104 wks. Baseline pt factors were self-reported; treatment history was abstracted from the medical record. Linear mixed-effect models were used to evaluate trajectories of weight change over the 104-wk WLI. Principal component analysis and multinomial models were used to examine distinct clusters of weight trajectories. Results: 3180 pts were enrolled from 637 sites between 8/2016 and 2/2021. FWRs were available from 1508 of 1591 WLI pts, with a total of 366,294 FWRs collected during the 2-yr WLI period. In pts with FWRs, mean baseline BMI was 34.4 ± 5.6 kg/m2, mean age was 53.2 ± 10.3 yrs, 10.8% self-identified as Non-Hispanic (NH) Black and 6.1% as Hispanic, 81.1% received chemo and 56.9% were postmenopausal. No statistically significant differences in baseline factors were observed between pts with and without FWRs. Intraclass correlation coefficient of baseline weights collected by study staff and by Fitbit scales was 0.99. In the WLI cohort, avg weekly weight (kg) decreased from 91.4 (95% CI: 90.6-92.3) at baseline to 85.6 (95% CI: 84.8-86.5) by wk 40, corresponding to a peak loss of 6.1% (95% CI: 5.7-6.4) of baseline weight. Weight remained stable until wk 52 and then gradually increased to 87.0 kg (95% CI: 86.2-87.9) at wk 104, corresponding to a 4.4% (95% CI: 4.0-4.8) loss at wk 104 vs. baseline. Principal component analysis identified 3 distinct weight trajectories: 67.6% of pts experienced peak weight loss of 6.6% (95% CI: 6.3-6.9) of baseline weight, 10.0% experienced peak loss of 17.5% (95% CI: 16.8-18.2) of baseline weight, and 22.4% did not achieve weight loss, gaining on avg 2.2% (95% CI: 1.7-2.6) of baseline weight. Pts with college (relative risk ratio [RRR]=1.41, 95% CI: 1.03-1.92) and post-graduate education (RRR= 1.58, 95% CI: 1.13-2.20) and those who were premenopausal (RRR=1.70, 95% CI: 1.28-2.26) were more likely to be in the cluster that did not lose weight. Pts who were NH White (RRR=3.60, 95% CI: 1.95-6.68), postmenopausal (RRR=1.94, 95% CI: 1.28-2.95), had no alcohol use (RRR=1.49, 95% CI: 1.03-2.16), had not received chemo (RRR=1.76, 95% CI: 1.15-2.72), and had <3 chronic conditions (RRR: 2.12, 95% CI: 1.23-3.66) were more likely to be in the cluster with the highest weight loss. Conclusion: Longitudinal weight data from BWEL demonstrate peak weight loss of 6.1% in the WLI cohort at 40 wks, with distinct trajectories indicating differential responses to the WLI. This work demonstrates the feasibility of using digital health tools to track outcomes in the setting of a large-scale weight loss intervention study and informs future precision behavioral interventions in oncology. Support: U10CA180821, U10CA180882, UG1CA189823; U10CA180863. https://acknowledgments.alliancefound.org. Citation Format: C. Cao, K. Ballman, L. McCall, C. Alfano, V. Bernstein, T. Crane, L. Delahanty, L. Frank, P. Goodwin, O. Hahn, D. Hershman, J. Hopkins, M. Irwin, E. Mayer, L. Minasian, L. Nebeling, M. Neuhouser, E. Paskett, P. Spears, V. Stearns, C. Thomson, T. Wadden, A. Weiss, J. White, C. Hudis, E. Winer, A. Partridge, L. Carey, J. Ligibel. Weight Trajectories in the Breast Cancer Weight Loss (BWEL) Trial (Alliance) [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PD8-01.