Primitive cerebral neuroectodermal tumors excluding medulloblastomas: a retrospective study of 30 cases

We present a retrospective study of 30 cases of primitive cerebral neuroectodermal tumors (PNET), excluding medulloblastomas, referred to us postoperatively for additional therapy to evaluate prognostic factors and treatment efficiency. The histologic types were: pinealoblastomas (n = 7); ependymoblastomas (n = 2); medulloepitheliomas (n = 4), and other PNET (n = 17). The tumor was located in the supratentorial area in 24 patients and in the posterior fossa in 6 patients. Among the supratentorial tumors, 8 were metastatic. Maximal surgical resection was performed. Sixteen of 30 patients had no measurable disease after surgery and were considered as standard-risk (SR) cases, and 14 with a local residue or metastasis as high-risk (HR) cases. The objective of postsurgical treatment was to avoid radiotherapy in children below 4 years of age. It consisted of radiotherapy alone in 6 patients, chemotherapy alone in 17, and radiotherapy with chemotherapy in 7. Furthermore, high-dose chemotherapy (busulfan, thiotepa) and autologous bone marrow transplantation, performed in 6 patients, yielded a response rate of 3/6. Event-free survival (EFS) of SR patients was 37% at 3 years (95% confidence interval (CI) 14-60%) and overall survival 44% (95% CI 26-62%). Only 1 of the HR patients achieved a complete remission and all of them died early. The critical prognostic factors appear to be the completeness of initial surgical resection and absence of metastasis. These tumors have a poor prognosis. Novel strategies (high-dose chemotherapy) are needed to improve their outcome because the children concerned are very young and the effects of radiotherapy are particularly deleterious when tumors are situated in the supratentorial area.