Results from a phase III randomized controlled study in China showed that Postmastectomy hypofractionated radiotherapy was non-inferior to and had similar toxicities to conventional fractionated radiotherapy in patients with high-risk breast cancer.However,reports of hypofractionated radiotherapy with two-stage expander/implant reconstruction are rare. Literatures report that reconstruction failure is a well-known complication of radiation therapy in breast cancer patients with reconstruction. Results may vary based on RT timing and technique. Some studies have shown that hypofractionated radiotherapy had similar reconstruction failure to conventional fractionated radiotherapy in patients with breast reconstruction. So,investigators conducted a phase II study to observe the reconstruction failure in hypofractionated radiotherapy with two-stage expander/implant reconstruction.