PROJECT SUMMARY Background. In the United States, 1 in 8 women will be diagnosed with breast cancer in their lifetime, with 1 in 39 women dying from the disease. While breast cancer is highly prevalent and can be deadly, in many cases it is treatable. Adjuvant endocrine therapy (AET) is an effective treatment for the 80% of women with early-stage disease who have hormone receptors expressed in their breast cancer. Although women who complete the recommended 10-year course of AET and consistently take the medication have a significantly reduced chance of recurrence, approximately half of women fail to complete this course of treatment. In addition to coping with debilitating menopausal-related side effects, women with breast cancer face psychosocial barriers that have been associated with poor AET adherence, including anxiety, depression, and poor social support. Importantly, these are modifiable constructs that may contribute to adherence and can be targeted by psychosocial interventions. Research Strategy. The current study aims to 1) test the long-term effects of two brief post-surgical psychosocial interventions, cognitive behavioral therapy (CBT) and Relaxation Training (RT), versus an attention-matched Health Education (HE) control (not focused on medication adherence), on AET adherence at 7 years post-baseline, 2) examine psychosocial mediators of trial effects on AET adherence, and 3) examine whether trial condition and AET adherence are related to 8-14-year recurrence- free survival. I have a unique opportunity to take advantage of an ongoing long-term follow-up from a cohort of women who participated in a randomized controlled trial for 5-week stress management and add measures to assess their adherence to AET and recurrence-free survival. Significance. Our prior work has demonstrated that CBT and RT effectively improved depressive affect, emotional well-being, and stress management skills in the intervention groups in comparison to those receiving the HE control. Given evidence that psychological distress relates to worse AET adherence, it is plausible that women receiving the intervention have had improvements in their AET adherence as a downstream effect of improvements in psychological wellbeing. This study will be the first to test whether a stress management intervention delivered post-surgery may have a long-term impact on AET adherence. If we can facilitate AET adherence early in the disease process through psychological intervention, we may ultimately improve long-term health outcomes. Training Plan. With additional training and experience in statistics, psycho-oncology, and adherence science, this study will lay the groundwork for my goal to become an independent clinical researcher. In line with the NCI’s mission of improving survivorship and helping people live longer, healthier lives, my long-term goals are to elucidate the behavioral processes underlying the effects of stress on cancer outcomes and to target these processes...