Heterogeneity of germline variants in high risk breast and ovarian cancer susceptibility genes in India

Breast and ovarian cancers now account for one in three cancers in Indian women and their incidence is rising. Major differences in the clinical presentation of breast and ovarian cancers exist between India and the United Kingdom. For example, Indian patients with breast cancer typically present a decade earlier than in the UK. Reasons for this could be multifactorial, including differences in underlying biology, environmental risks, and other systematic factors including access to screening. One possible explanation lies in variable incidence or penetrance of germline mutations in genes such as BRCA1 and BRCA2. We performed a methodical database and literature review to investigate the prevalence and spectrum of high-risk cancer susceptibility genes in Indian patients with breast and ovarian cancers. We identified 148 articles, but most studies were small, with inconsistent inclusion criteria and based on heterogeneous technologies, so that mutation frequency could not be reliably ascertained. Data were also often lacking on penetrance, histopathology, and survival outcomes. After filtering out unsuitable studies, only 13 remained, comprising 1028 patients. Large-scale research studies are urgently needed to determine mutation prevalence, spectra, and clinico-pathological features, and hence derive guidelines for screening, treatment, and prevention specific to the Indian population.