Receptor subtype and outcome of breast cancer - Single-center experience from North India.

Aims/objectives: In resource-limited settings, data regarding the impact of molecular/receptor subtypes on breast cancer (BC) are sparse. In this single-center retrospective study from north India, we analyze the outcomes of various molecular subtypes of BC.

Materials and methods: Females with biopsy-proven BC who were treated at our State Cancer Institute from 2014-2018 were included. Data regarding clinicopathological parameters and follow-up details were evaluated. For data analysis, cancers were categorized into 4 subtypes: HR+HER2-, HR+HER2+, HR-HER2+, and HR-HER2-.

Results: Among 944 patients included, HR+HER2- (49.1%) and HR+HER2+ (13.1%) were the most and least common subtypes, respectively. The receptor subtype significantly impacted overall survival (OS). HR+HER2- cancers had the best outcomes while HR-HER2- cancers fared worst (3-yr OS of 94.3% and 69.1%, respectively). On subgroup analysis, the molecular subtype continued to significantly impact OS in patients with tumor grades II and III, disease stages II and III, and age groups of <40 and 40-60 years, respectively (HR-HER2- cancers had the lowest cumulative survival in each subgroup). In patients with metastatic BC, all molecular subtypes except HR+HER2- had a dismal prognosis.

Conclusions: Overall and across various subgroups, patients with triple-negative BC had the poorest outcomes. Ensuring optimal treatment utilization including affordable access to personalized tailored therapy is the need of the hour to improve long-term outcomes in these patients.