A Whole Food, Plant-based Randomized Controlled Trial in Metastatic Breast Cancer: Feasibility, Nutrient, and Patient-reported Outcomes

Purpose: Quality of life (QOL) is among the most important outcomes for women with metastatic breast cancer (MBC), and it predicts survival. QOL is negatively impacted by cognitive impairment, fatigue, and weight gain. We assessed whether a whole food, plant-based (WFPB) diet-promoting weight loss is feasible and might improve QOL.

Methods: Women with MBC on stable systemic treatments were randomized 2:1 to 1) WFPB dietary intervention (n = 21) or 2) usual care (n = 11) for 8 weeks. Participants attended weekly education visits and consumed an ad libitum WFPB diet (3 prepared meals/day provided). Patient-reported outcomes and 3-day food records were assessed at baseline and 8 weeks. The effects of WFPB diet on changes in outcomes were assessed by analysis of covariance model controlling for baseline.

Results: 20 intervention and 10 control participants completed the trial. Intervention participants were highly adherent to the WFPB diet (94.3 % total calories on-plan). Intervention group nutrient intakes changed significantly including dietary fat (35.8 % to 20.4 % percent calories from fat, p < 0.001) and fiber content (12.7 to 30.8 g fiber/1000 kcal, p < 0.001). Perceived cognitive function (FACT-Cog total + 16.1; 95 % confidence interval [CI] = 0.8-31.7; p = 0.040) and emotional well-being (FACT-B emotional well-being subscale + 2.3; CI = 0.5-4.1; p = 0.016) improved in the WFPB versus the control group. Fatigue, measured by the BFI, improved within the WFPB group for fatigue severity (M = 4.7 ± 2.5[SD] to 3.7 ± 2.3, p = 0.047) and fatigue at its worst (5.8 ± 2.8 to 4.4 ± 2.4, p = 0.011).

Conclusions: Significant dietary changes in this population are feasible and may improve QOL by improving treatment-related symptoms. Additional study is warranted.

Trial Registration: ClinicalTrials.gov identifier: NCT03045289. Registered 7 February 2017.