Treatment outcomes and late toxicities in patients with embryonal central nervous system tumors

Standard treatment strategies for embryonal central nervous system (CNS) tumors have not yet been established. We treated these tumors using an original chemoradiation therapy protocol; the clinical outcomes and toxicities were retrospectively evaluated.

Twenty-four patients were enrolled including sixteen with medulloblastoma, four with supratentorial primitive neuroectodermal tumor (sPNET), three with atypical teratoid/rhabdoid tumor, and one with pineoblastoma. Immediately after diagnosis, all patients underwent surgery initially. They were then categorized as high- or average-risk groups independent of tumor type/pathogenesis. The average-risk group included patients who were aged ≥3 years at diagnosis, had non-metastatic disease at diagnosis (M0), and had undergone gross total resection. Other patients were categorized as the high-risk group; this group received more intensive treatment than the average-risk group, including high-dose chemotherapy with autologous stem-cell transplantation. All patients received craniospinal irradiation (CSI). The CSI dose was 23.4 Gy for M0 patients aged ≥5 years, 18 Gy for M0 patients aged <5 years, and 30-36 Gy for all patients with M + disease. The total dose to the primary tumor bed was 54 Gy.

The median follow-up time was 73.5 (range, 19-118) months. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 71.1 and 88.9%, respectively in the average-risk group (n = 9) and 66.7 and 71.1%, respectively in the high-risk group (n = 15). The PFS and OS rates were not significantly different between the average- and high-risk groups. In patients with medulloblastoma only, these rates were also not significantly different between the average- and high-risk groups. Three of four patients with sPNET were disease free. The height standard deviation score (SDS) was significantly decreased at the last assessment relative to that at diagnosis (P < 0.0001). The latest median height SDS was -1.6 (range, 0.9 to -4.8), and the latest median full-scale intelligence quotient (FSIQ) score was 86 (range, 59-128). The CSI doses and age at the start of radiation therapy did not influence clinical outcomes, height SDSs, and FSIQ scores.

Our original protocol for patients with embryonal CNS tumors was feasible and yielded favorable clinical outcomes.