# Bilateral Primary Breast Cancer With Discordance in Molecular Subtypes: A Case Report

## TL;DR

This case report describes a rare instance of bilateral breast cancer with differing molecular subtypes and discusses its implications.

## Contribution

The novelty lies in presenting a rare case of synchronous bilateral breast cancer with discordant molecular subtypes.

## Key findings

- Discordance in molecular subtypes was observed in a case of synchronous bilateral breast cancer.
- Such discordance may be associated with a poorer prognosis.
- The case highlights the need for further research on this rare phenomenon.

## Abstract

Molecular subtype is a crucial prognostic factor for bilateral breast cancer and plays a key role in guiding treatment decisions. Several studies have confirmed that the expression patterns of hormone receptor and human epidermal growth factor receptor 2 are generally consistent in synchronous bilateral primary breast cancer. Discordance in the receptor expression status is commonly associated with poorer prognosis in synchronous bilateral breast cancer. However, there is currently limited literature reporting such cases. This article presents a case of synchronous bilateral primary breast cancer with discordant molecular subtypes and reviews relevant literature.