BRCA1, short for Breast Cancer 1 protein, is a crucial tumor suppressor gene [1,2,3]. It is involved in fundamental cellular functions such as DNA repair, transcriptional regulation, and cell cycle control in response to DNA damage [2]. BRCA1 is essential for maintaining genome integrity in all cells, and its reduced expression due to mutations or epigenetic inactivation can lead to impaired mammary gland differentiation and an increased risk of breast cancer development [1].

Mutations in the BRCA1 gene predispose individuals to breast and ovarian cancers, yet it remains unclear why other cancer types are not as commonly associated [1,2,5]. In ovarian cancer, BRCA1 germline mutations cause hereditary cases, and its epigenetic inactivation contributes to sporadic cases. Evidence suggests BRCA1 may be a biomarker for response to platinum-based chemotherapy in ovarian cancer, with BRCA1 deficiency predicting enhanced response, while loss of its function may reduce response to antimicrotubule-based chemotherapy [6]. For breast cancer, risk-reducing mastectomy in women with BRCA1 pathogenic variants can lower the risk of breast cancer and the probability of dying from it [4].

In conclusion, BRCA1 is vital for maintaining genomic stability through its role in DNA repair and other cellular processes. Its malfunction is strongly linked to breast and ovarian cancers. Studies, including those on individuals with BRCA1 mutations, have provided insights into the role of BRCA1 in these cancers, which may guide preventive and treatment strategies for these diseases.