Combining systemic therapies with radiation in breast cancer

Over the last years, significant survival benefits for breast cancer were derived from the use of postoperative systemic therapies and radiotherapy. Although these two modalities have been extensively used, the optimal strategies of their combining remain debatable. There have been few randomized studies addressing this issue and their results are generally inconclusive. This article reviews combining systemic therapies (chemotherapy, hormonotherapy and trastuzumab) with radiation in breast cancer patients. In clinical practice, chemotherapy and radiotherapy are most commonly used sequentially but this strategy is not based on level 1 evidence. Increased cardiotoxicity and skin reactions preclude the concomitant radiotherapy and anthracycline-based chemotherapy. Further investigations are warranted to determine the safety of taxane-based schedules used concomitantly with radiotherapy, particularly with regard to pneumotoxicity. Concurrent chemo-radiotherapy with the use of selected schemes may be considered in patients with locally advanced cancer but this strategy still needs to be verified in large randomized studies. The optimal combination of tamoxifen and aromatase inhibitors with radiotherapy has also not been determined in randomized trials and the results of retrospective studies are inconsistent. Finally, the data on combining targeted therapies with radiation are still scarce and do not allow for meaningful conclusions.