Clinical Relevance of Immunohistochemical Subtypes in Early-Stage, Lymph Node-negative Breast Cancer. Results of a Large Cohort Study

Aims

This study aimed to provide the association of immunohistochemical (IHC) subtypes of early-stage, lymph node–negative breast cancer with clinical outcomes. The relevance of adjuvant systemic therapy (AST) with respect to triple-negative cancers was given special attention.

Materials and methods

We used the data of 1,959 breast-conserving therapies (BCTs) in 1,861 women diagnosed with early-stage unilateral, lymph node–negative breast cancer treated between 2004 and 2015.

Results

Overall, IHC subtypes were not associated with disease-specific survival (DSS) or overall survival (OS) in multivariate analyses. Looking at the influence of AST, administered according to current guidelines, we noted that triple-negativity compared to luminal A demonstrated a better DSS (hazard ratio [HR]: 0.4, 95% confidence interval [CI]: 0.1-1.1). For those without AST, outcomes for all subtypes did not differ. Difference in outcome of triple-negative tumours for without and with AST was mainly due the presence of patients bearing histological grade 3 cancers in those without AST.

Conclusion

In early-stage, lymph node–negative breast cancer treated with BCT and AST, according to existing guidelines, triple-negativity demonstrated a better outcome in DSS. However, for those without AST, no differences were seen in outcome between the various subtypes.