Whole Food Plant-Based Lifestyle Adaptation for Nutrition Therapy in Patients with Metastatic Breast Cancer: The PLANT-MBC Study in NCORP - Project Summary Despite advances in treatment, women with metastatic breast cancer (mBC) experience debilitating symptoms— including fatigue, cognitive impairment, and treatment-related weight gain—that diminish quality of life (QOL) and may accelerate disease progression. Existing dietary interventions are limited and often narrowly targeted (for example, ketogenic diets tested with specific therapies), with few strategies designed to broadly improve symptom burden and survivorship across all mBC subtypes. To fill this gap, our team conducted a rigorous eight- week pilot randomized trial demonstrating that a whole-food, plant-based (WFPB) dietary intervention improved QOL, reduced treatment-related symptoms, and favorably altered biomarkers of cancer progression in women with mBC, with high acceptability and adherence. Building on these promising results, this U34 planning grant will evaluate the feasibility, sustainability, and preliminary efficacy of a 26-week remotely delivered WFPB intervention, preparing for a future Phase III randomized controlled trial. We will enroll 80 participants with mBC (BMI ≥25 kg/m²) from diverse racial, ethnic, and socioeconomic backgrounds across NCORP community oncology sites. Participants randomized to the intervention arm will receive prepared frozen meals that taper over time, transitioning to grocery deliveries and self-directed meal planning with structured support. The program also includes daily plant-based protein shakes, a multivitamin, and education and coaching informed by the Transtheoretical Model and Social Cognitive Theory. Control participants will receive group-based general health education and grocery cards to match the time, attention, and financial support provided to the intervention arm. The study has three primary aims: (1) Facilitate recruitment and retention across NCORP sites, including medically underserved populations; (2) Assess operational feasibility, adherence, and sustainability of the WFPB intervention in diverse community settings; and (3) Evaluate preliminary impacts on QOL, treatment-related symptoms (fatigue, cognition, body weight), and exploratory biomarkers of cancer progression. Stakeholder engagement is central to this project. We will conduct semi-structured interviews, quarterly advisory board meetings, and post-intervention feedback sessions with clinicians, staff, patients, and advocates to guide refinement of materials, workflows, and implementation strategies. Rigorous mixed-methods analyses will generate essential data to optimize recruitment, delivery, and measurement approaches for a definitive multicenter trial. Findings will inform the design of a fully powered Phase III trial to determine whether a remotely delivered WFPB diet improves QOL, reduces symptom burden, and impacts clinical outcomes in women with mBC. This project leverages the strong research infrastructure of the URCC NCORP Research Base and builds on robust pilot data, representing an innovative, scalable strategy to address symptom management and survivorship in this underserved population.
