Is there an increased risk of spinal relapse in standard-risk medulloblastoma/primitive neuroectodermal tumor patients who receive only a reduced dose of craniospinal radiotherapy?

Akıncı Burcu, Çetingül Nazan, Özdemir Özgür, Kamer Serra, Kantar Mehmet, Aksoylar Serap, Demirağ Bengü, Vergin Canan, Öniz Haldun, Kansoy Savaş, Turhan Tuncer, Akalın Taner, Ertan Yeşim, Kitiş Ömer, Anacak Yavuz

Medulloblastoma (MBL) is the most common pediatric brain malignancy. Postoperative radiotherapy to the entire craniospinal axis is the standard-of-care but has linked to long-term morbidity. In this study, we analyzed the implication of reduced dose craniospinal radiotherapy (RT) for survival and pattern of relapse in MBL patients. The clinical characteristics of 32 consecutively diagnosed medulloblastoma/primitive neuroectodermal tumor patients were analyzed. After surgical resection, a dose of 23.4 Gy of spinal RT with a posterior fossa boost of 30.6 Gy was prescribed to standard-risk patients, whereas high-risk patients received 36 Gy spinal RT with additional boosts to the posterior fossa up to 54 Gy. Then, both groups received the same chemotherapy protocol. Five-year OS for standard and high-risk patients was 94 and 50%, respectively. When analyzing prognostic factors, postoperative tumor size is the most important one which affects the OS. Ten patients relapsed during follow-up, and there was no isolated spinal relapse in either group. The risk of isolated spinal relapse does not increase with reduced-dose craniospinal RT, since there is no isolated relapse in either the standard or high-risk groups of patients.