Immunohistochemical Expression of Alpha Smooth Muscle Actin in Infiltrating Ductal Carcinoma of Breast and its Association with Histopathological and Hormonal Status: A Cross-sectional Study

Abstract

Introduction: Breast carcinoma is the second most common cancer and cause of death worldwide, with a mortality rate of 15%. Among various theories regarding the pathogenesis of cancer, the tumour microenvironment is known to play an essential role in cancer development and progression. Aim: To determine the expression of alpha Smooth Muscle Actin (α-SMA) in infiltrating ductal carcinoma of breast carcinoma and its association with histopathological parameters and hormonal receptors status. Materials and Methods: This was a cross-sectional observational study done in Department of Pathology, RL Jalappa Hospital, a tertiary care centre, Karnataka, India from January 2018 to December 2022. A total of 100 cases of Infiltrating Ductal Carcinoma confirmed by histopathological examination were included in the study. All the Haematoxylin and Eosin (H&E)- stained slides were screened for histological type, tumour grade, and nodal metastasis and Immunohistochemistry (IHC) markers like Oestrogen Receptor (ER), Progestrone Receptor (PR), Ki67, Human Epidermal growth factor 2 neu (HER2/neu) and α-SMA were performed. Results: 54% of the subjects were positive for ER, 52% of the subject was positive for PR, and 30% of the subjects were HER2/neu. 53% of the subjects had >14% Ki67 and 47% of the subjects had <14% Ki67.According to molecular typing, 38% was luminal A, 20% was luminal B, Triple-Negative Breast Cancer (TNBC) was present in 30%, and HER2/neu positivity was seen in 12%. According to Nottingham Prognostics Index (NPI), patients were grouped into four categories according to the NPI score: I (excellent) was 15%; II (good) was 36%, III (moderate) was 32%; and IV (poor) was 17%. Conclusion: SMA positivity can be used as an important prognostic factor in infiltrating ductal carcinoma as its stromal expression is associated with grade of the tumour and lymph node status.