Clinicopathological Parameters of HER2 Low Breast Cancers

This was a retrospective cohort study which included all histologically proven cases of breast cancer in the 2 years from January 2022- December 2023 at a tertiary care centre. This study was performed in line with STROCSS criteria. The following clinicopathological data was retrieved from the histopathological records- age, tumor size, nodal involvement, lymphovascular/ perineural invasion, and Bloom Richardson grading. Routine histopathological processing was done followed by immunohistochemical analysis for ER, PR, HER2, Ki67 and AR. All the cases were categorised into Luminal A, B, Her2 enriched and triple-negative breast cancer based on the surrogate molecular classification. Further, all the cases were categorised into HER2 negative (no staining or incomplete weak membrane staining in ≤10% tumor cells), HER2 3+ (complete membranous staining) and HER2 low (1-2+ staining without amplification on ISH) based on consensus of two pathology consultants. The present study aims to evaluate the clinicopathological parameters of the HER2 low breast cancers.