Germline BRCA1 Mutation inSquamous Cell Carcinoma of Oesophagus: Driver versus Passenger Mutation

Abstract

We report a rare case of 62-year-old South Asian women who visited the Molecular Pathology and Genomics Department for hereditary germline cancer genetic testing after being diagnosed with oesophageal cancer, reported as invasive keratinizing squamous cell carcinoma metastasized to the lymph nodes. Her personal history revealed that she was diagnosed with triple-negative breast cancer five years before oesophageal cancer. Germline cancer testing showed pathogenic variants in BRCA1 gene c.68_69delAG, which proved it a hereditary breast and ovarian cancer syndrome. She was started on PARP inhibitors but developed some secondary respiratory failure and succumbed to death. Less than 10 cases have been reported in the literature of the association of germline BRCA1 and Squamous cell Carcinoma – the esophagus. The article focuses on the probable pathogenesis of BRCA1 mutation with non-classic malignancies and the response of Poly adenosine diphosphate ribose polymerase inhibitors (PARP) inhibitors in such a scenario. We report an unusual manifestation of the BRCA1 gene with second primary oesophageal squamous cell cancer occurring five years later to triple-negative breast cancer.