Evaluating Dose Timing (Morning vs Evening) of Endocrine-based Therapies in Metastatic Breast and Prostate Cancers

The REaCT-CHRONO-MetBP Pilot study will compare morning and evening administration of endocrine-based therapy in metastatic breast and prostate cancers. Participants with metastatic breast or prostate cancer will be randomly placed in one of two groups: a morning group and an evening group. The group assignment will determine whether they take their endocrine therapy in the morning or the evening. The primary outcome of this pilot study is to evaluate the feasibility of study procedures in order to conduct a larger definitive trial in the future. The secondary outcomes include comparing quality of life, tolerability, and efficacy outcomes between the morning and evening groups for each of the two cancer cohorts (metastatic breast and prostate cancer).