Plant-Based Nutrition for Breast or Endometrial Cancer

This is a randomized controlled trial of a whole food, plant-based (WFPB) dietary intervention among women with metastatic breast or endometrial cancer. It is designed to explore whether this dietary intervention is sustainable in this population for 26 weeks and whether improvements in quality of life and cardiometabolic health demonstrated in a previous study are sustained. If so, this study will gather information to know whether these benefits translate into reduced overall mortality and cancer markers when compared with a control group that is matched for time and attention but does not implement dietary change. The intervention consists of a whole food plant-based dietary program, group education and individual coaching/visits while the control group gets general wellness group education and individual visits while maintaining their usual diet.

Inclusion criteria

• Female sex (as assigned at birth), aged 18 years or older

• A confirmed diagnosis of endometrial or metastatic breast cancer. All subtypes are eligible
• Treating oncologist approval and expected survival of at least six months
• Undergoing any systemic treatment including hormonal, cytotoxic, targeted monoclonal antibody or small molecule kinase inhibitors or any combination of the above. Women who have active cancer and have been recommended but declined systemic treatment are also eligible.
• Willing to adopt a strict, whole-foods, plant-based diet
• Willing and able to comply with the WFPB protocol for the duration of the study including scheduled testing, Zoom meetings, and office visits
• Able to speak and read English fluently.
• Women with plans for radiation therapy or surgery are also eligible provided that they meet all other eligibility criteria.

Exclusion criteria

• BMI ≤ 20.0 kg/m2

• Inability to tolerate a normal diet
• Active malabsorption syndrome at time of consent, as determined by study physicians (i.e. Crohn's disease, bowel surgery)
• Any food allergies or intolerances that would interfere with study compliance
• Recent consumption (in the past six months) of a vegan diet
• eGFR < 30 on ≥ two lab tests in the past six months
• Serum potassium > 5.4 in the past six months
• Current insulin or sulfonylurea use
• Current warfarin use (non-vitamin K antagonist allowed)
• High-risk alcohol use (>7 drinks/wk)
• Illicit substance use (not including marijuana)
• Cognitive impairment or psychiatric disorder impairing ability to give consent.