Abstract: Early-onset breast cancer has aggressive clinicopathological characteristics and worse prognosis. However, there are few studies about it at home and abroad, which restricts the improvement of diagnosis and treatment level of breast cancer. Compared with older breast cancer, early-onset breast cancer has high mutation frequency and wide mutation spectrum. The study of unique susceptibility genes of early-onset breast cancer not only helps elucidate the difference of germline mutation spectrum between early-onset breast cancer and older breast cancer, but also will be helpful to study the diagnostic and prognostic marker for breast cancer, which provides evidence for screening and precision therapy.

Key words: Breast neoplasms, Age of onset, Mutation, Genetic predisposition to disease