Abstract
PURPOSE: Preclinical studies have indicated that physical exercise may enhance chemotherapy efficacy. However, clinical trials are needed to investigate these findings. We hypothesized that an exercise program during neoadjuvant chemotherapy would improve tumor response in patients with breast cancer. PATIENTS AND METHODS: Neo-train was a randomized controlled trial allocating patients with breast cancer to the usual care control (CON) group or the exercise (EX) group that received supervised high-intensity interval training and progressive resistance training 3 times weekly during 18 to 24 weeks of neoadjuvant chemotherapy. The two groups were compared on tumor size, assessed using magnetic resonance imaging as primary outcome, and secondary clinical/pathologic, biological, physical, and patient-reported outcomes. RESULTS: From 2021 to 2023, 102 participants were randomly assigned to the EX (n = 50) or CON (n = 52) group. We found no between-group differences in median tumor size change from baseline to presurgery (EX vs. CON -3.0 mm [95% confidence interval (CI), -8.0 to 14.0]), the proportion with radiologic complete response [EX 65% vs. CON 56%; odds ratio 1.16 (95% CI, 0.39-3.91)], or pathologic complete response [EX 59% vs. CON 56%; odds ratio 1.03 (95% CI, 0.43-2.46)]. The exercise program was associated with higher relative dose intensity, fewer dose delays, shorter hospital stays, and increased cardiorespiratory fitness, muscle strength, and level of physical activity. We found no differences in tumor-infiltrating lymphocytes, body composition, health-related quality of life, anxiety, depression, psychological distress, or participation in rehabilitation between groups. CONCLUSIONS: Although the exercise program did not affect tumor size, the positive effects on chemotherapy completion and shorter hospitalizations suggest improved treatment tolerance.