An Audit of 1000 Breast Cancer Cases with Molecular Subtype Analysis from a Tertiary Care Cancer Centre in India

Breast cancer represents a substantial global health challenge and stands as a predominant cancer among women in India. Globally, it ranks as the fifth leading cause of cancer-related deaths. The advent of molecular classification has revolutionized the approach to treating breast cancer. In this study, we aimed to assess the prevalence of various molecular subtypes within breast cancer patients in our state. It was a prospectively conducted study in a tertiary care cancer center over a period of 2 years from November 2020 to October 2022. A total of 1003 breast cancer patients which included both metastatic and non-metastatic cases who underwent treatment were evaluated. All patients had their molecular subtyping done by immunohistochemistry (IHC), and fluorescence in situ hybridization (FISH) testing was further performed in equivocal cases. The intrinsic classification of breast cancer endorsed by the St. Gallen Consensus Conference was used to subtype the cases. The results were presented in terms of means and standard deviations, while categorical data were represented as frequencies and proportions. Among the 1003 patients included in the study over 2 years, 999 were females and 4 males with a median age of 54 years. In total, 92.2% and 7.8% were non-metastatic and metastatic respectively. The most common molecular subtype was luminal B (53.3%) followed by TNBC (22.1%), luminal A (13.2%), and HER2-enriched (11.4%). Among the 912 operated cases, 572 (62.7%) and 340 (37.2%) underwent BCS and mastectomy respectively. ER score increases with an increase in age in contrast to PR score which decreases with age. Overall, HER2/neu receptor status was positive in 26.7% (268 out of 1003 patients) and has a positive correlation with increase in age. In our study, we have analyzed the distribution patterns of molecular subtypes in breast cancer within the Northern Kerala region. The findings of our study reveal a striking similarity between the observed patterns in Northern Kerala and those documented both regionally and globally. This convergence not only underscores the consistency of the molecular subtypes across diverse geographical areas but also emphasizes the significance of our research in contributing valuable insights to the broader understanding of breast cancer epidemiology.