Primary care continuity and breast cancer survival: a retrospective cohort study

Primary care provider (PCP) continuity improves many health outcomes, but its impact on breast cancer survival remains unclear. We examined how baseline PCP continuity and use (in the 24 months before diagnosis) relate to overall survival in Ontario women with breast cancer.

Population-based, retrospective cohort study, using linked provincial-level administrative health databases and cancer registries, including 13,171 women in Ontario diagnosed with stage I-III breast cancer between 2007 and 2012 who received curative surgery and adjuvant chemotherapy. We used Cox proportional hazards regression to examine the association between baseline PCP continuity and use with overall survival, determined up to 31 December 2020, adjusting for age, comorbidity, neighborhood income, and immigration status, and examined cancer stage as a potential mediator.

No PCP visits in the 24 months before diagnosis were associated with worse survival (HR for death 1.27, 95% CI 1.08-1.49). For those with PCP visits, low versus high continuity was not associated with survival in our adjusted analyses (HR 0.98, 95% CI 0.90-1.07). Treated linearly, each additional PCP visit in the 24 months before diagnosis, regardless of continuity, was associated with slightly worse survival (HR 1.01 per visit, 95% CI 1.00-1.01).

Baseline PCP continuity was not associated with overall survival in women with breast cancer in Ontario after adjusting for potential confounders. However, having no baseline PCP visits, or having a higher overall number of baseline PCP visits were associated with lower survival. Further research can clarify whether ensuring patients have access to any PCPs at baseline or providing added support for patients with many baseline PCP visits after a breast cancer diagnosis can improve survival outcomes.