Background
Peer support, social support provided by individuals with shared lived experience, is widely recognized as an effective approach to address psychosocial distress and improve treatment adherence, quality of life, and engagement with care among newly diagnosed cancer patients. In limited-resource settings, where psycho-oncology services and workforce capacity are constrained, scalable peer-led models offer a pragmatic strategy to strengthen comprehensive and person-centered cancer care However, evidence remains limited on how peer support interventions can be systematically adapted and translated across settings to support public health action. 

Objectives
To describe the development, cultural adaptation, and scaling of Stronger Together (ST), an evidence-based peer-to-peer psychosocial support model, from an initial evaluation in Viet Nam, to toolkit development and subsequent implementation and evaluation among women newly diagnosed with breast cancer in Rwanda, with ongoing implementation in Ethiopia. 

Methods
ST was first culturally adapted and evaluated in Viet Nam through an NCI-funded trial using an implementation science-informed framework to ensure contextual relevance and acceptability. Findings informed the development of a standardized implementation toolkit, led by Global Focus on Cancer (GFC), to support replication across resource settings. The toolkit was subsequently applied in  Rwanda through collaboration with the Women’s Cancer Relief Foundation (WCRF), and public healthcare facilities. Women were matched with trained peer mentors using a structured training and supervision model. Outcomes were assessed at baseline and 2, 4, and 6 months and included the DASS-21, the NCCN Distress Thermometer, and the EORTC QLQ-C30. Cancer-related stigma and treatment continuation were monitored. Qualitative data focus group discussions and in-depth interviews with patients, mentors, and healthcare providers examined acceptability, feasibility, benefits, and implementation barriers and facilitators.

Results
In the Rwandan implementation, 69 women newly diagnosed with breast cancer enrolled at baseline across three districts. Mixed-effects models demonstrated statistically significant reductions in psychosocial distress from baseline to six months, including anxiety (mean change −1.46, p=0.0121), depression (−2.02, p=0.0006), and stress (−1.76, p=0.0019). Distress scores declined over follow-up, while global health status/quality of life improved significantly (mean score 61.8 to 74.6; p=0.0006). Cancer-related stigma scores were significantly lower at follow-up (p=0.0025). Participants receiving peer support completed treatment without documented abandonment. Qualitative findings indicated high acceptability; participants reported reduced isolation and fear, increased hope, improved understanding of treatment, and support in addressing stigma. Peer mentors reported increased confidence, while healthcare providers noted improved patient engagement, appointment adherence, and continuity of care. Implementation challenges included transportation and communication costs.

Conclusions/Implications:
This work demonstrates a pathway for translating psychosocial cancer care research into public health action in limited-resource settings, moving from cultural adaptation and evaluation in Viet Nam to toolkit development and implementation in Rwanda, with improvements consistent with patterns reported in the earlier Viet Nam evaluation.  Ongoing implementation in Ethiopia, using the same standardized instruments under oncologist leadership, highlights the model’s transferability and readiness for evaluation across additional health system contexts. As a low-cost, capacity-building intervention grounded in civil society engagement, Stronger Together offers a scalable model for strengthening comprehensive cancer control beyond clinical treatment alone.

DASS 21