Proton craniospinal irradiation versus photon involved-field radiotherapy for solid tumor leptomeningeal metastasis

Photon involved-field radiotherapy (IFRT) is the standard-of-care RT for leptomeningeal metastasis (LM) from solid tumors; however, it does not stop progression of LM along the neuroaxis. A randomized phase 2 trial at Memorial Sloan Kettering Cancer Center (New York, NY) compared proton craniospinal irradiation (pCSI) encompassing the entire CNS versus IFRT for LM from non-small cell lung cancer and breast cancer. pCSI resulted in significantly improved CNS progression-free survival, meeting the primary end point of the study, which led to early discontinuing of the trial at plannen interim analysis. pCSI also showed overall survival advantage compared with IFRT with no increase in high-grade adverse events.