Radiation therapy is a crucial part in the comprehensive treatment of breast cancer. In recent years, emerging systemic treatment regimens such as HER 2 inhibitors, CDK 4/6 inhibitors, PARP inhibitors, capecitabine and PD1 inhibitors have greatly improved the prognosis of breast cancer and has become the standard treatment for specific populations. A considerable number of patients require both radiotherapy and maintenance systemic therapy. However, it is not clear whether systemic therapy should be synchronized or suspended in radiotherapy，despite that previous basic research shows that some molecular drug therapy and radiotherapy has a clear synergy mechanism. There is an agent need for a definite evidence to evaluate the safety of synchronous treatment, to support clinical diagnosis and treatment and the next step of comprehensive treatment. The implementation of the new radiotherapy technology represented by IMRT takes into account the prescription dose homogenization and the minimization of normal tissue dosage, which provides a certain basis for the combination therapy. Based on the above conditions, this study intends to enroll patients between 18 and 70 years old with chest wall / breast ± lymphatic drainage area and requiring capecitabine, CDK 4/ 6 inhibitor, HER2 targeted therapy or immunotherapy. Radiation and novel systemic therapies would be delivered concurrently. The study aimed at evaluating the safety of combined treatments.

Inclusion Criteria:

ECOG 0-2. Aged 18-70 years old. Pathologically diagnosed as breast cancer. Need to receive radiotherapy according to guidelines. Radiotherapy target volume included chest wall/breast with or without lymph node regions.

Need to receive one of the following therapies according to guidelines, capetabine, CDK4/6 inhibitor, PARP inhibitor , ICIs , HER2 inhibitors.

Exclusion Criteria:

Male breast cancer. Allergy to the upper medicines before. Will receive trastuzumab alone during and/or after radiotherapy. With severe other disease.