Although there is no data on the toxicity with concurrent bevacizumab and hormonal therapy, the combination is not expected to increase toxicity seen when given as a single agent. Abnormal tumor microenvironments, tumor progression, and metastatic spread are major factors contributing to treatment failures in radiotherapy. Anti-VEGF agents (e.g. bevacizumab) can help overcome these factors through several different mechanisims.
Studies also demonstrate prolonged use of anti-VEGF agents with radiation therapy was more effective at preventing metastases from irradiated tumors compared to a short course. Patients generally start hormonal therapy and daily radiotherapy at the same time. This study will delay the start of radiotherapy until 8 weeks after the start of hormonal therapy and bevacizumab.
