Discussion
depressive, Depression, depressive symptoms, breast cancer
SECONDARY, BREAST CANCER
Depression is a common problem among breast cancer survivors that results in significant burden and has implication for long-term survival. Behavioral interventions that target an increase in physical activity may have a role in reducing depressive symptoms among breast cancer survivors. Results of the current analysis indicate that depressive symptoms were reduced across a sample of over 300 breast cancer survivors. Through the factorial design, we identified one specific behavioral intervention strategy, ALED, that resulted in significant reductions in depressive symptoms.Results of the current analysis are in contrast to findings of the primary outcoming analysis (under review). In that analysis, participants who engaged in the supervised exercise sessions demonstrated greater engagement and MVPA at six months compared to those participants who did not receive supervised exercise. No other intervention strategy significantly increased MVPA. However, participants engaged in the ALED intervention engaged in less light physical activity. Those findings, combined with the fact that change in physical activity was not correlated with changing depressive symptoms suggest that characteristics of the ALED intervention beyond physical activity engagement might be responsible for the change in depressive symptoms observed.ALED is behavior change program designed around skill development in goal-setting, identifying and addressing barriers, and building social support. While within ALED these skills are targeting changes in physical activity behavior, it is possible that the development of these skills has application in other aspects of life that could positively impact depressive symptoms. For example, it has been postulated that goal-setting and goal pursuit may improve depressive symptoms [It should be noted that our findings should not suggest that increasing physical activity cannot improve depressive symptoms among breast cancer survivors. In fact, the overall decrease in depressive symptoms observed across the entire study population would suggest increasing physical activity can improve depressive symptoms among breast cancer survivors. Instead, our findings have potentially important implications in the aim to optimize behavioral interventions for breast cancer survivors. In the PACES trial, the primary outcome was MVPA and our primary outcome analysis found that supervised exercise sessions were the only intervention strategy that significantly increased MVPA. However, supervised sessions did not significantly improve depressive symptoms in the current analysis. These findings suggest that multiple outcomes might be considered when determining an “optimal” intervention for a population and that a more personalized approach might be warranted.The results presented should be interpreted with consideration of the strengths and limitations of the study. The factorial design allowed for concurrent evaluation of the effect of multiple intervention components on depressive symptoms. However, the design does not provide a true “control” condition; therefore, it is possible that some of the improvement in depressive symptoms observed was due to factors beyond intervention participation. We note that depressive symptoms was a secondary outcome. However, the large sample size provided the necessary power to detect a significant effect of ALED. The focus of this paper was on depressive symptoms; however, multiple outcomes and individual factors could ultimately inform what is the “optimal” intervention for a particular group, subgroup, or individual.Our findings have both scientific and practical implications. Scientifically, the results highlight the need for future research identifying factors to inform intervention optimization. Ultimately our findings reinforce the concept of intervention optimization as an iterative process. As noted by Collins et al. [