Correlation of Calretinin Immunostaining with Molecular Subtypes and Clinicopathological Parameters in Breast Carcinoma

Background: Breast cancer is one of the most predominant malignancies worldwide, with diverse molecular subtypes influencing prognosis and treatment approaches.This study evaluated Calretinin expression in invasive breast carcinoma and its correlation with molecular subtypes and clinicopathological parameters.Methods: This study was an observational, cross-sectional study at the Himalayan Institute of Medical Sciences, where tissue samples from 96 patients were analyzed through histopathological and immunohistochemical evaluation.Calretinin expression was assessed using a scoring system based on nuclear and/or cytoplasmic staining intensity and the percentage of positive tumor cells. Results:The results exposed significant variation in Calretinin expression across different molecular subtypes (p=0.000).Luminal A and HER2-enriched subtypes showed predominantly low expression, whereas Triple Negative Breast Cancer showed the highest levels, with 71% of cases demonstrating moderate-to-high expression.A significant correlation was also observed between Calretinin expression and histological tumor grade (p =0.000), with high expression levels more frequently associated with Grade III tumors.Conclusion: Calretinin could serve as a possible biomarker for aggressive breast cancer subtypes, predominantly TNBC.Its association with high tumor grade and proliferation indices designates a possible role in tumor progression, the importance of its prognostic and diagnostic significance.Additional studies are required to establish its potential use in therapeutic decision-making.