Breast cancer susceptibility gene 1 expression in breast cancer patients and its correlation with histopathological features using the immunohistochemical method in the Indian population

Abstract

Background: Pathogenic mutations in breast cancer susceptibility gene 1 (BRCA1) are the common causes for germline as well as sporadic aggressive subtypes of breast cancer. This study was conducted to know BRCA1 expression in breast cancer by immunohistochemistry (IHC) testing.
Methods: This was a cross-sectional study conducted in the Department of Medical Oncology, Vardhman Mahavir Medical College and Safdarjung hospital, New Delhi, from July 2016 to April 2018. The patients with confirmed diagnosis if breast cancer and aged >18 years were included in the study. BRCA1 expression, estrogen/progesterone receptor (ER/PR) status, and Human epidermal growth factor receptor 2 (Her 2-neu) were evaluated by IHC in all patients.
Results: Of the 50 patients enrolled, the mean (± standard deviation) age was 53 (±11.76) years; 17 (34%) were in the range of 41–50 years, while 13 (26%) were in the range of 51–60 years. The distribution of patients with breast cancer according to risk factors showed that family history of cancer was present in 8 (16%), prebenign breast disease in 5 (10%), use of hormone replacement therapy/oral contraceptives pills in 31 (62%), exposure to radiation in 2 (4%) and history of smoking in 15 (30%) patients. Metastasis was seen in
43 (86%) patients and the prevalence of BRCA1 was 8% (n = 4); three patients in the age group of 41–50 years and one patient in the age group of 31–40 years. A negative BRCA1 expression was observed in 46 (92%) patients; 40/46 patients had >40 years and 39/46 patients had no family history of cancer. Similarly, of the 17 and 33 pre‐ and post‐menopausal patients, 16 and 30 patients had negative BRCA1 expression, respectively. BRCA1 expression was negative in all the ER/PR receptor and Her‐2‐neu‐positive patients. Histological Grade II tumors were observed in 26 (52%) patients, of whom 22 patients showed negative BRCA1 expression.
Conclusion: The prevalence of BRCA1 among breast cancer patients was 8%. Studies with larger sample size are needed to further assess BRCA1 gene mutations and determine clinical usefulness as a potential biomarker by IHC.