Histopathology and Immunohistochemical Profile of Breast Cancer amongst Young Females below 40 years of Age: A Cross-sectional Study

Abstract

Introduction: Breast cancer is a diverse and heterogeneous disease affecting women in both developing and developed countries. In 2022, Global Cancer Observatory (GLOBOCAN) reported 2.3 million cases of breast carcinoma, which accounted for 11.6% of all cancer cases worldwide. The incidence of breast cancer in India has been steadily rising and has surpassed cervical cancer as the most common cancer in women. Invasive ductal carcinoma is the most common histologic type found in all age groups. Grading is done according to Elston Ellis’s modification of the Scarff Bloom Richardson Scoring system. Hormonal {Estrogen Receptor (ER), Progesterone Receptor (PR)} and Human Epidermal growth factor Receptor-2 (HER2/neu) immunohistochemical expression are used for molecular typing of breast carcinoma. Young women account for up to 25% of all breast carcinoma cases in India. Aim: To assess the clinical symptoms, histological type, grade, Immunohistochemistry (IHC) profile (ER, PR, HER2neu), and their relationships in females below 40 years of age with breast carcinoma. Materials and Methods: An ambispective cross-sectional study with a total of 99 cases of breast carcinoma in young females were included in the study, which was conducted in the Department of Pathology at Sri Aurobindo Medical College and PG Institute in Indore, Madhya Pradesh, India, between April 2022 and March 2024. Biopsies, lumpectomy, and total or modified mastectomy specimens were fixed in formalin and paraffin embedded. Sections were stained with Haematoxylin and Eosin (H&E) and IHC markers ER, PR, and HER2neu using Estrogen Receptor Alpha Antibody (EP1), EP2, and EP3 antibodies, respectively, on a fully automated workstation. Carcinomas were classified according to the World Health Organisation (WHO) classification and graded based on Elston Ellis’s modification of the Scarff Bloom Richardson System Scoring. The proportion of tumour cells and intensity were studied, and evaluation was done with appropriate controls. Results: The most common symptom was a breast lump (84.84%), while Invasive breast cancer of {No Special Type (NST)} was the most common histologic type (96.96%) and histological Grade III was predominant (53.53%) in the majority of patients. ER, PR, and HER2neu were positive in 57.57%, 51.51%, and 33.33% of cases, respectively. HER2neu expression was negative in the majority of cases (66.66%). The most common molecular subtype was Luminal A (35.35%), followed by Triple-negative Breast Cancer (TNBC) (29.29%), Luminal B (22.22%), and the least common was the HER2neu enriched subtype (13.13%). Conclusion: Invasive breast carcinoma (NST) is the most common histologic type, with higher histologic grade and a greater number of triple-negative cases seen in young females (<40 years).

Keywords

• histological grade
• invasive breast carcinoma
• molecular subtypes
• triple-negative breast cancer