MULTIVARIATE-ANALYSIS OF PROGNOSTIC FACTORS IN ADULT PATIENTS WITH MEDULLOBLASTOMA - RETROSPECTIVE STUDY OF 156 PATIENTS

Background. Medulloblastoma is a rare disease in adult patients, with an annual incidence rate of 0.05 per 100,000 per year. Results are, therefore, sparse and comprise small series over long periods. The real survival rate, the prognostic factors, the optimal postoperative radiation dose, and the role of adjuvant chemotherapy are still unknown for this disease in adults. Methods. The authors collected 156 cases of histologically proven medulloblastoma in patients older than 18 years of age who were treated between January 1975 and December 1991 in 13 French institutions. They analyzed the prognostic factors for survival and the impact of postoperative treatment on survival. Results. The 5- and 10-year event free survival rates, 61 and 48%, respectively, are similar to those observed in children. The median time to recurrence is 30 months, but late relapses after 5 years remain frequent. Multivariate analysis identified postoperative performance status, spinal axis radiation dose, fourth ventricular floor involvement, and desmoplastic histologic subtype as factors significantly correlated with event free survival. No benefit of concomitant chemotherapy was demonstrated, and complete resection resulted only in severely reduced postoperative performance status. Conclusions. The prognostic factors in adult medulloblastoma are comparable to those of medulloblastoma in children, but a new parameter, postoperative performance status, was identified in this adult series. Postoperative craniospinal irradiation remains the standard treatment for adults with medulloblastoma. A reduced dose to the supratentorial compartment should be tested in a prospective protocol.