Associations of pre-diagnosis physical activity with treatment tolerance and treatment efficacy in breast cancer patients with neoadjuvant chemotherapy

Purpose: Higher pre-diagnosis physical activity (PA) is associated with lower all-cause mortality in breast cancer (BCa) patients. However, the association with pathological complete response (pCR) is unclear. We investigated the association between pre-diagnosis PA level and chemotherapy completion, dose delay, and pCR in BCa patients receiving neoadjuvant chemotherapy (NACT). Methods: 180 stage I–III BCa patients receiving NACT (mean [SD] age of diagnosis: 60.8 [8.8] years) in the Sister Study were included. Self-reported recreational and total PA levels were converted to metabolic equivalent of task-hours per week (MET-hrs/wk). The pCR was defined as no invasive or in situ residual in breast or lymph node (ypT0 ypN0). Multivariable logistic regression analyses estimated odds ratios (ORs) and 95% confidence intervals (CIs) for treatment outcomes. Results: In this sample, 45 (25.0%) BCa patients achieved pCR. Higher pre-diagnosis recreational PA was not associated with lower likelihood of chemotherapy completion (highest vs. lowest tertile: OR = 0.87, 95% CI = 0.30–2.56; P_trend = 0.84), greater dose delay (OR = 1.45, 95% CI = 0.54–3.92; P_trend = 0.46), or greater odds of pCR (OR = 1.28, 95% CI = 0.49–3.34; P_trend = 0.44). Associations were similar for pre-diagnosis total PA. Meeting the recommended level of recreational PA was not associated with pCR overall (≥ 7.5 vs. < 7.5 MET-hrs/wk: OR = 1.33, 95% CI = 0.59–3.01). Conclusions: Although small sample size and limited information on exercise closer to time of diagnosis limit interpretation, pre-diagnosis PA was not convincingly associated with treatment tolerance or treatment efficacy in BCa patients receiving NACT. Future investigations are needed to better understand the impact of pre-diagnosis PA on BCa treatment.