Purpose: Successful completion of chemotherapy is critical to improve breast cancer outcomes. Relative dose intensity (RDI), defined as the ratio of chemotherapy delivered to prescribed, is a measure of chemotherapy completion and is associated with cancer mortality. The effect of exercise and eating a healthy diet on RDI is unknown. We conducted a randomized trial of an exercise and nutrition intervention on RDI and pathologic complete response (pCR) in women diagnosed with breast cancer initiating chemotherapy.
Methods: One hundred seventy-three women with stage I-III breast cancer were randomly assigned to usual care (UC; n = 86) or a home-based exercise and nutrition intervention with counseling sessions delivered by oncology-certified registered dietitians (n = 87). Chemotherapy dose adjustments and delays and pCR were abstracted from electronic medical records. T-tests and chi-square tests were used to examine the effect of the intervention versus UC on RDI and pCR.
Results: Participants randomly assigned to intervention had greater improvements in exercise and diet quality compared with UC (P < .05). RDI was 92.9% ± 12.1% and 93.6% ± 11.1% for intervention and UC, respectively (P = .69); the proportion of patients in the intervention versus UC who achieved ≥85% RDI was 81% and 85%, respectively (P = .44). The proportion of patients who had at least one dose reduction and/or delay was 38% intervention and 36% UC (P = .80). Among 72 women who received neoadjuvant chemotherapy, women randomly assigned to intervention were more likely to have a pCR than those randomly assigned to UC (53% v 28%; P = .037).
Conclusion: Although a diet and exercise intervention did not affect RDI, the intervention was associated with a higher pCR in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative and triple-negative breast cancer undergoing neoadjuvant chemotherapy.
Trial registration: ClinicalTrials.gov NCT03314688.