Photon Craniospinal Irradiation for the Treatment of Leptomeningeal Disease Secondary to Breast Cancer or Non-small Cell Lung Cancer

This phase II trial tests how well craniospinal irradiation (CSI) using photon volumetric modulated arc radiotherapy (VMAT) works in treating patients with breast cancer or non-small cell lung cancer (NSCLC) that has spread from the original (primary) tumor to the cerebrospinal fluid and meninges (thin layers of tissue that cover and protect the brain and spinal cord) (leptomeningeal disease). Radiation therapy uses high energy x-rays, particles, or radioactive seeds to kill cancer cells and shrink tumors. CSI (radiation therapy directed at the brain and spinal cord to kill tumor cells) may be able to target all of the areas of possible leptomeningeal tumor spread. Photon-VMAT-CSI may be an effective treatment option for patients with leptomeningeal disease secondary to breast cancer or NSCLC.