Study Protocol for the Social Interventions for Support During Treatment for Endometrial Cancer and Recurrence (SISTER) study: a community engaged national randomized trial.

Aim: Social isolation in cancer patients is correlated with prognosis and is a potential mediator of treatment completion. Black women with endometrial cancer (EC) are at increased risk for social isolation when compared with White patients. We developed the Social Interventions for Support during Treatment for Endometrial Cancer and Recurrence (SISTER) study to compare and evaluate interventions to address social isolation among Black women with high-risk EC in USA. The primary objective of the SISTER study is to determine whether virtual support interventions improve treatment completion compared with Enhanced Usual Care. Secondary objectives include comparing effectiveness virtual evidence-based interventions and evaluating barriers and facilitators to social support delivery. Patients & methods: This is a multi-site prospective, open-label, community-engaged randomized controlled trial, consisting of three intervention arms: enhanced usual care, facilitated support group and one-to-one peer support. Primary outcome will be measured using relative dose. Qualitative semi-structured interviews will be conducted with a subset of participants to contextualize the relative degree or lack thereof of social isolation, over time. Data analysis: Primary analysis will be based on an intent-to-treat analysis. Multivariable analysis will be performed to determine the effect of the intervention on the primary and secondary outcomes of interest, relative dose and social isolation score. Semi-structured interviews will be qualitatively analyzed using inductive and deductive approaches of content analysis. Discussion/conclusion: Endometrial cancer mortality disproportionately affects Black women, and social isolation contributes to this disparity. The SISTER study aims to identify whether and to what extent differing social support vehicles improve key outcomes for Black women in the United States with high-risk EC. Clinical Trial Registration: NCT04930159 (ClinicalTrials.gov).