High chromosome instability identified by low-pass whole-genome sequencing assay is associated with TP53 copy loss and worse prognosis in BRCA1 germline mutation breast cancer.

CIN-high is a prognostic factor correlated with shorter DFS and was independent with the germline BRCA1 mutation pattern. Higher CIN values were significantly correlated with TP53 copy loss in breast cancer patients with germline BRCA1 mutation. Our results revealed a reliable molecular parameter for distinguishing patients with poor prognosis from the BRCA1-mutated breast cancer patients.