Immunohistochemical Profile and Molecular Subtype Distribution of Breast Carcinoma at a Tertiary Care Centre in Western Rajasthan

Introduction: Breast cancer is a heterogeneous disease, and immunohistochemistry-based molecular subtyping serves as a marker for intrinsic classification. The distribution of molecular subtypes shows considerable regional variation across India, with important implications for prognosis and treatment planning.

Aim: To evaluate the immunohistochemical profile and molecular subtype distribution of breast carcinoma cases at a tertiary care centre in western rajasthan.

Materials and Methods: This retrospective observational study included 239 cases of histopathologically confirmed invasive breast carcinoma. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status were assessed using standard immunohistochemistry protocols. Molecular subtypes were classified into luminal A, luminal B, HER2-enriched, and triple-negative breast cancer (TNBC) based on surrogate immunohistochemical markers. Data were analysed descriptively.

Results: ER positivity was observed in 226 cases (94.6%), and PR positivity in 228 cases (95.4%). HER2 overexpression (3+) was identified in 82 cases (34.3%). Luminal A was the most common molecular subtype (153 cases, 64.0%), followed by luminal B (78 cases, 32.6%). HER2-enriched and triple-negative subtypes were infrequent, accounting for 4 cases each (1.7%).

Conclusion: The present study demonstrates a marked predominance of luminal breast cancer subtypes with a comparatively low frequency of TNBC. While luminal dominance is consistent with several Indian studies, the low TNBC prevalence highlights significant regional and methodological variation. Specific molecular profiling remains essential for understanding local disease pathology and optimizing personalized breast cancer management.