Long-Term Dietary Changes and Mortality Among Participants of a Whole Food Plant-Based Pilot Study for Metastatic Breast Cancer.

Background There are limited data on dietary interventions among women with metastatic breast cancer. We previously conducted a feasibility trial of a whole-food, plant-based (WFPB) diet in 32 women with metastatic breast cancer randomized 2:1 to WFPB (n=21) or control (n=11). The 8-week intervention provided meals and weekly visits and resulted in beneficial changes but was not designed to support long-term behavior change. Objective Given impressive short-term benefits, we wanted to know whether any dietary changes persisted even in the absence of support. Methods We attempted to contact and re-consent survivors for a descriptive follow-up consisting of a 3-day food diary and quality-of-life questionnaires; medical records were reviewed to ascertain survival status. Two participants (1 control, 1 intervention) were withdrawn shortly after randomization in the pilot and were not included in this follow-up. Results Overall, 2/20 (10%) participants originally assigned to the intervention and 5/10 (50%) assigned to control had died by the time of chart review. Among surviving participants, 11/18 intervention and 2/5 control participants completed the follow-up assessment, which occurred, on average, 5 years after their last study visit. Among intervention participants who completed dietary follow-up, mean energy intake remained lower. Though the intake of most food groups returned toward baseline, intake of refined grains and added fats remained lower at follow-up. Conclusion In this small, exploratory, long-term follow-up, research participants maintained selective dietary changes 5 years after completing an 8-week intervention. Though mortality differences require cautious interpretation, these descriptive findings suggest that longer, adequately powered studies are warranted. Trial registration First registered at Clinicaltrials.gov (NCT03045289) on February 7, 2017.