Impact of tumor location and fourth ventricle infiltration in medulloblastoma

Medulloblastoma is the most common intracranial malignancy in children; with comprehensive treatment the 5-year overall survival (OS) is now greater than 80 %. Only few studies have addressed the relation of tumor location with patient's prognosis. Based on experiences in our institution, we further classified the tumor location. This study aimed to investigate the impact of tumor location and fourth ventricle infiltration in medulloblastoma (MB) prognosis.

We retrospectively followed all MB patients at the Beijing Tiantan Hospital between 2004 and 2007 to investigate treatment outcomes and prognostic factors in MB patients. The data of 119 patients were collected. Tumor removal was performed in all patients, and all patients received postsurgical radiotherapy or chemotherapy. The patients were subclassified into three subtypes according to tumor location and tumor infiltration into the fourth ventricular floor (V4 floor). The prognostic factors were analyzed using Kaplan-Meier and Cox regression analysis.

The median follow-up period was 75 months (range, 6-127 months). A total of 65 patients experienced recurrence or progression, and 56 patients were still alive at the time of follow-up. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 47.1 ± 4.6 % and 54.6 ± 4.6 %, respectively.

According to the multivariate analysis, large cell and anaplastic (LC/A) subtype, patient age, and metastasis were found to be independent prognostic factors. Tumors with V4 floor infiltration exhibited a trend toward recurrence (P = 0.054). This investigation is the largest single-institution study of MB cases in China. The LC/A subtype, patient age, and metastasis were important prognostic factors. V4 floor infiltration was correlated with metastasis and younger age.