Cancer
Tailored physical activity strategies and mortality among breast cancer survivors: a target trial emulation Emma McGee* Emma McGee McGee McGee McGee McGee McGee McGee McGee McGee McGee Harvard T.H. Chan School of Public Health
Background: Guidelines recommend individualized (i.e., tailored) physical activity strategies for cancer survivors. However, there is limited data on the causal effects of these strategies on long-term mortality outcomes for breast cancer survivors.
Methods: We specified the protocol of a target trial that approximately mirrored the Colon Health and Lifelong Exercise Change (CHALLENGE) randomized trial but was conducted among breast cancer survivors with stage II or III disease. We used observational data from the Pathways Study, a prospective cohort of individuals enrolled in the Kaiser Permanente Northern California health plan with invasive breast cancer, to emulate this first target trial. Then, we used data from the Pathways Study to emulate a second target trial examining the effects of more pragmatic, tailored physical activity strategies on mortality in a broader population of breast cancer survivors with stage I-III disease.
Results: In the first target trial, there were 959 eligible individuals and 183 deaths. Compared with a health-education strategy, a recreational aerobic activity strategy was associated with an 8.0 percentage point (95% CI: 3.4, 13.3) reduction in 8-year all-cause mortality, which was consistent with the CHALLENGE trial (7.1 percentage point reduction [95% CI: 1.8, 12.3]). In the second target trial, there were 2,107 eligible individuals and 321 deaths, 139 of which were due to breast cancer. Compared with no intervention, a strategy requiring tailored increases of 60 minutes of vigorous or 120 minutes of moderate aerobic activity per week was associated with a 3.1 percentage point (95% CI: 2.0, 4.6) reduction in 10-year all-cause mortality and a 2.4 percentage point (95% CI: 1.2, 3.5) reduction in 10-year breast cancer-specific mortality.
Conclusions: Pragmatic strategies requiring tailored increases in physical activity levels may reduce 10-year mortality among breast cancer survivors.
