Breast cancer molecular subtypes based on MRI diagnosis

impact on surgical plan

Abstract

Background: Breast cancer (BC) is the most common cancer affecting women worldwide. In 2022, about 2.3 million new cases and 670,000 deaths were reported globally according to World Health Organization, making it a major public health problem. BC is divided into four molecular subtypes according to the way certain genes express themselves, including hormone receptors (estrogen and progesterone receptors), HER2 expression and proliferation index. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) has shown crucial role in identifying the characteristic morphological pattern of the different molecular subtypes. Aim of the study was to assess the impact of MRI on the choice of optimal surgical plan for different molecular subtypes of breast cancer. Methods: This prospective study included forty patients diagnosed with breast cancer who underwent immunohistochemistry followed by contrast enhanced MRI. They were all candidates for upfront surgery. Results: The study was done at time interval between June 2022-October 2023. The mean age of selected patients was 51.6 ± 9.8 years. The most dominant molecular subtype was luminal (26/40) followed by HER2 (10/40) and triple negative (4/10). Luminal subtype was strongly associated with spiculated margins, while HER2/neu tumors and TNBC showed circumscribed and irregular margins respectively (p=0.0077). Heterogeneous enhancement was dominant in luminal and HER2/neu cancers, while TNBC showed rim enhancement (p=0.0059). Regarding management, luminal subtypes were mostly managed by breast conservative surgery, while HER2/neu and triple negative were managed by mastectomy. A significant association was found between the molecular subtype and the surgical plan (p < 0.013).  Conclusion: MRI morphological pattern of different molecular subtypes can be an acceptable predictor for the optimal surgical plan for each type.