Expression of c-Myc in Invasive Breast Carcinoma of No Special Type: A Cross-sectional Study

Introduction: Breast cancer is the most common malignancy among women worldwide, accounting for approximately 30% of all female cancers. It is the second leading cause of cancer-related mortality among women globally, with a median age of 61 years at diagnosis. Aberrant expression of c-Myc leads to genomic instability and tumourigenesis. Cellular Myelocytomatosis Oncogene (c-Myc) regulates the Tumour Microenvironment (TME) and plays a role in angiogenesis and stromal cell proliferation. Its overexpression in Invasive Breast Carcinoma (IBC) is associated with poor prognosis. Targeting c-Myc may offer therapeutic benefits, as its inhibition sensitises breast cancer cells to chemotherapy and radiotherapy. However, its role in diagnosis and treatment of IBC warrants further evaluation. Aim: To study the expression of c-Myc in Invasive Breast Carcinoma of No Special Type (NST). Materials and Methods: The present cross-sectional study was conducted at KIMS, Bhubaneswar, Odisha, India, from March 2023 to March 2025, and included 55 histologically confirmed cases of IBC. Immunohistochemistry (IHC) for Oestrogen Receptor (ER), Progesterone Receptor (PR), Human Epidermal Growth Factor Receptor-2 (HER2/neu), Ki-67, and c-Myc was performed in all cases. c-Myc expression was evaluated, and overexpression was defined as ≥20% of tumour cells showing moderate to strong nuclear staining. The association of c-Myc overexpression with various clinicopathological parameters, including age, laterality, histological grade, Ductal Carcinoma In Situ (DCIS), Lymphovascular Invasion (LVI), Perineural Invasion (PNI), tumour stage, nodal stage, nodal status, ER, PR, HER2/ neu status, molecular subtypes, and Ki-67 index, was analysed. Statistical analysis was performed using IBM Statistical Package for Social Sciences (SPSS) version 26. The Pearson’s chi-square test was used for categorical variables, and a p-value