This study compared the incidence of hypothyroidism, growth hormone deficiency (GHD), and adrenal insufficiency (AI) in patients with medulloblastoma following craniospinal irradiation (CSI) of photon or proton. For the 118 patients who were followed for a median of 5.6 years from the end of radiotherapy, the study found that 31% patients developed hypothyroidism, 66% GHD, and 18% AI. Compared to PBT, XRT was associated with a higher incidence of primary hypothyroidism (28% vs. 6%; p = 0.03). Central hypothyroidism, GHD, and AI incidence rates were similar between the groups.