Introduction: Observational studies suggest that physical activity after a breast cancer diagnosis is associated with improved cancer outcomes; however, no randomized data are available. Here, we report an exploratory follow-up of cancer outcomes from the Supervised Trial of Aerobic versus Resistance Training (START).
Methods: The START Trial was a Canadian multicenter trial that randomized 242 breast cancer patients between 2003-2005 to usual care (n = 82), supervised aerobic (n = 78) or resistance (n = 82) exercise during chemotherapy. The primary endpoint for this exploratory analysis was disease-free survival (DFS). Secondary endpoints were overall survival (OS), distant disease-free survival (DDFS), and recurrence-free interval (RFI). The two exercise arms were combined for analysis (n = 160) and selected subgroups were explored.
Results: After a median follow-up of 89 months, there were 25/160 (15.6%) DFS events in the exercise groups and 18/82 (22.0%) in the control group. Eight-year DFS was 82.7% for the exercise groups compared with 75.6% for the control group (Hazard ratio [HR]= 0.68, 95% CI = 0.37-1.24; log-rank p = 0.21). Slightly stronger effects were observed for OS (HR = 0.60, 95% CI = 0.27 to 1.33; log-rank p = 0.21), DDFS (HR = 0.62, 95% CI = 0.32 to 1.19; log-rank p = 0.15), and RFI (HR = 0.58, 95% CI = 0.30 to 1.11; Gray's p = 0.095). Subgroup analyses suggested potentially stronger exercise effects on DFS for women who were overweight/obese (HR = 0.59, 95% CI = 0.27-1.27), had stage II/III cancer (HR = 0.61, 95% CI = 0.31-1.20), ER positive tumors (HR = 0.58, 95% CI = 0.26-1.29), HER2 positive tumors (HR = 0.21, 95% CI = 0.04-1.02), received taxane-based chemotherapies (HR = 0.46, 95% CI = 0.19-1.15), and >= 85% of their planned chemotherapy (HR = 0.50, 95% CI = 0.25-1.01).
Conclusions: This exploratory follow-up of the START Trial provides the first randomized data to suggest that adding exercise to standard chemotherapy may improve breast cancer outcomes. A definitive phase III trial is warranted.
(C) 2014 American College of Sports Medicine