A pilot study of risk-adapted radiotherapy and chemotherapy in patients with supratentorial PNET

We undertook this study to estimate the event-free survival (EFS) of patients with newly diagnosed supratento-rial primitive neuroectodermal tumor (SPNET) treated with risk-adapted craniospinal irradiation (CSI) with additional radiation to the primary tumor site and subsequent high-dose chemotherapy supported by stem cell rescue. Between 1996 and 2003, 16 patients with SPNET were enrolled. High-risk (HR) disease was differentiated from average-risk (AR) disease by the presence of residual tumor (M₀ and tumor size > 1.5 cm²) or disseminated disease in the neuraxis (M₁-M ₃). Patients received risk-adapted CSI: those with AR disease received 23.4 Gy; those with HR disease, 36-39.6 Gy. The tumor bed received a total of 55.8 Gy. Subsequently, all patients received four cycles of high-dose cyclophosphamide, cisplatin, and vincristine with stem cell support. The median age at diagnosis was 7.9 years; eight patients were female. Seven patients had pineal PNET. Twelve patients are alive at a median follow-up of 5.4 years. The 5-year EFS and overall survival (OS) estimates for all patients were 68% ± 14% and 73% ± 13%. The 5-year EFS and OS estimates were 75% ± 17% and 88% ± 13%, respectively, for the eight patients with AR disease and 60% ± 19% and 58% ± 19%, respectively, for the eight with HR disease. No deaths were due to toxicity. High-dose cyclophosphamide- based chemotherapy with stem cell support after risk-adapted CSI results in excellent EFS estimates for patients with newly diagnosed AR SPNET. Further, this chemotherapy allows for a reduction in the dose of CSI used to treat AR SPNET without compromising EFS.