Abstract Background: Physical activity is related to reduced mortality and recurrence in breast cancer patients, as well as fewer severe adverse effects during and following its treatment. The potential of exercise as a concurrent therapy for inhibiting primary tumor growth has been suggested by preclinical and observational studies. However, the impact of exercise on efficacy of neoadjuvant chemotherapy (NAC) for early breast cancer is unclear and prospective controlled studies are lacking. Therefore, we aimed to perform a meta-analysis exploring the effect of exercise training during NAC on the pathologic complete response (pCR) in breast cancer. Methods: We systematically searched PubMed, EMBASE and Cochrane databases for randomized controlled trials (RCTs) that compared exercise training or usual care during NAC in breast cancer patients. The primary endpoint of interest was pCR. Subanalyses were performed for pCR by breast cancer subtype. Heterogeneity was examined with I2 statistics. A random-effects model was used for outcomes with high heterogeneity. The protocol of this systematic review is registered with PROSPERO under the identifier CRD420251142764. Results: We included 5 RCTs with 465 patients undergoing NAC, met the inclusion criteria for this meta-analysis, of whom 258 (55.4%) received training. The mean age ranges from 48.4 to 52.3 years on the exercise training group and 45.0 to 53.3 years on control group. The pooled pCR rate was 51.5% in the exercise group compared with 46.3% in the usual care group. Overall, there was no significant difference between groups (odds ratio OR 1.28; 95% confidence interval CI 0.83-1.98). Similarly, the subgroup analysis revealed that pCR in breast cancer subtype hormone receptor-positive HER2-negative (OR 2.50; 95% CI 0.74-8.42), HER2-positive (OR 1.17; 95% CI 0.54-2.53) and triple negative (OR 1.19; 95% CI 0.40-3.54) were not significantly different between groups. Conclusion: Our meta-analysis suggests that the exercise training during neoadjuvant chemotherapy is not significantly different from usual care on breast cancer pathological complete response. Citation Format: V. D. L. Rosa, R. R. Alves, C. S. Anjos, R. M. S. Rahal, D. V. G. Santana, L. R. Soares, C. A. Vieira, R. Freitas-Junior. Effect of exercise training during neoadjuvant chemotherapy on breast cancer pathological complete response 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 PS4-11-15.
Rosa et al. (Tue,) studied this question.