Project Summary/ Abstract: This F31 award will allow Kelsey Sinclair (PI) the research training that will advance her toward her goal of becoming an independent cancer multimorbidity scientist with an expertise in intervention adaptation and implementation to optimize cancer care in underserved groups. Cancer-obesity co-morbidity is common and especially deadly for Black breast cancer survivors (BCS). Although Black women have lower breast cancer incidence, they have the highest breast cancer mortality rate (40%) of any U.S. race/ethnic group – an effect attributed in part to comorbid obesity and systemic health disparities. Obesity predicts higher mortality among Black BCS, and post-cancer diagnosis weight gain predicts increases in mortality. Treatment inequities due to intersecting weight/race stigma also contribute to cancer screening/treatment delays. One way to fight back against these disparities is to develop and to deliver obesity treatments adapted to address the unique challenges of the Black BCS community. Identification of important risk/protective factors can be applied to evidence-based weight loss interventions to provide inclusive, equitable, and potentially life-extending care. Thus, the proposed multi-method study will use a socioeconomic framework and multi-methods to discover actual risk/protective factors for Black BCS with obesity compared to other BCS. PI Sinclair will leverage resources from a parent trial to first use a quantitative survey to assess 100 BCS from any race-ethnicity to test potential risk and protective factors that differ for Black BCS (Phase 1). Second, using co-design qualitative methods, initial tailoring of an evidence-based weight loss intervention for obesity will be done in collaboration with our patient partners – five Black BCS with obesity (Phase 2). This tailored weight loss protocol will then be delivered in a pilot with 15 Black BCS with obesity, with preliminary evaluation of potential treatment heterogeneity factors (Phase 3). Via these phases, the following F31 aims will be addressed: Aim 1: To proactively identify cultural and multimorbid factors of an obesity intervention for Black BCS and Exploratory Aim 2: To explore obesity treatment response in Black BCS via subgroup analyses. We hypothesize that Black women with obesity will report the highest risk scores and lowest protective scores, that qualitative interviews will identify important factors that may not have been captured quantitatively, and that variables that emerged as relevant with adequate variability across the sample will impact treatment response. The proposed F31 will thus utilize Phase 1 survey data and Phase 2 qualitative interviews (Aim 1) as well as Phase 3 post-treatment data (Exploratory Aim 2). Accordingly, it will benefit from the existing parent pilot infrastructure (e.g., recruitment strategies, participants, trial conduct). For the parent trial, the outcomes are acceptability, feasibility, and preliminary weig...