An increasing number of new systemic therapy agents are being incorporated into the treatment of breast cancer, and sometimes it seems there’s little thought about how those agents may interact with radiation. Here are multidisciplinary consensus recommendations from ESTRO on how to integrate novel breast cancer therapies with radiation. Immunotherapy was felt to be relatively safe during locoregional radiation and palliative radiation. HER2 targeted therapies (not antibody-drug conjugates, ADCs) were felt to be safe when given with locoregional radiation and palliative radiation with the exception of newer HER2 TKIs for which the authors recommended more prospective data. They also emphasized a need for more data on the combination of radiation and CDK 4/6 inhibitors. These recommendations typically mean there’s limited data with no obvious contraindications, but caution should be exercised when combining with radiation. Similar recommendations were made for HER2 ADCs except that T-DM1 should be avoided with brain radiation. The authors recommended against concurrent PARP inhibitors outside clinical trials. Finally, they recommended against concurrent RT and PI3K inhibitors as well as mTOR inhibitors. | Meattini, Lancet Oncol 2024
