Regional Variations in Guideline Concordance for Women with Triple-Negative and HER2+ Breast Cancer in Nova Scotia

Background: Systematic neoadjuvant therapy (NAT) is recommended for triple-negative (TNBC) and HER2+ breast cancers when tumor size at diagnosis is ≥2 cm. This study aimed to determine the proportion of patients in Nova Scotia with non-metastatic, incident, ≥2 cm TNBC and HER2+ breast cancer who received guideline-concordant NAT, stratified by administrative zone. Methods: This retrospective analysis utilized data from the Nova Scotia Breast Screening Program. Adult patients (18-80 years) with an incident, non-metastatic, ≥T2 breast cancer diagnosis between 2021 and 2023 were considered theoretically eligible for NAT, defined by a wait time of ≥4 months between core biopsy and surgery. Guideline-concordant care was confirmed through chart review and compared across health system administrative zones and over time. Results: Of the 291 women theoretically eligible for NAT, 67.0% received it. Significant differences in NAT receipt were observed across administrative zones (Central 73.1%, Eastern 72.9%, Northern 57.4%, Western 54.2%, p = 0.030). Conclusions: This study identifies meaningful regional disparities in NAT receipt for TNBC and HER2+ breast cancer in Nova Scotia. Targeted strategies to improve guideline concordance are warranted and may lead to better patient outcomes.