# Online peer support for breast cancer survivors: protocol for a decentralized multicenter open-label pilot randomized controlled trial (HOPE-BC study)

## TL;DR

This study tests online peer support for breast cancer survivors and aims to develop a matching algorithm to improve future support programs.

## Contribution

The study introduces a novel approach to explore patient-supporter matching in online peer support for breast cancer survivors.

## Key findings

- The study will assess the effectiveness of online peer support using the UCLA Loneliness Scale.
- It will explore factors influencing satisfaction to guide matching algorithm development.
- Effect sizes will be calculated to inform future trials.

## Abstract

The effectiveness of peer support for breast cancer survivors has varied substantially, and no previous study has examined patient–supporter matching. This study protocol describes a decentralized, multicenter, open-label pilot randomized controlled trial designed to explore the effectiveness of online peer support for breast cancer survivors and to develop a matching algorithm for use in future research.

Fifty breast cancer survivors within 3 years of completing initial treatment will be recruited and will provide electronic informed consent. They will be randomly assigned to either the peer support group, which will schedule a peer support session immediately after registration, or the waitlist control group, which will schedule their session 2 weeks later. Peer support sessions will be conducted online by two trained peer supporters. The primary outcome is the score on the UCLA Loneliness Scale, assessed 1 week after the session in the peer support group and at the end of the 2-week waiting period in the control group. Secondary outcomes include satisfaction with peer support and other psychosocial measures, all assessed through an electronic patient-reported outcome system. Effect sizes will be calculated to inform sample size estimation for future trials. Potential factors associated with satisfaction, such as similarity between participants and peer supporters, will also be explored to guide matching algorithm development.

The findings will inform a future confirmatory trial incorporating an optimized matching algorithm.

Trial registration UMIN000056741.

The online version contains supplementary material available at 10.1007/s10147-026-02979-3.