Purpose: Retrospective analysis of patients with medulloblastoma to determine the effectiveness of previous treatments for medulloblastoma and plan for future management strategies.
Methods and materials: During the period March 1976 to December 1991, 172 patients with cerebellar medulloblastoma were referred to King Faisal Specialist Hospital and Research Center. One hundred and forty-nine patients were treated with curative intent. There were six postoperative deaths, and 10 patients planned for radiotherapy treatment failed to complete the prescribed course. One hundred and thirty-three patients completed a course of radiotherapy after surgery. Adjuvant chemotherapy was not used routinely (six patients only). Tumors were staged retrospectively according to the Chang staging system. There were no T1 patients, 32 patients had T2 tumors, 76 had T3 tumors, and 29 had T4 tumors. The T stage could not be allocated in 12 patients. Ninety-nine patients required a shunting procedure either pre- or postoperatively. Forty-six patients had complete resection of tumor, 91 had incomplete resection, and 6 patients had biopsy only. The extent of resection could not he determined in six patients. The median radiation dose for the whole brain was 34 Gy, spine 32.5 Gy, and posterior fossa 52.8 Gy. Fraction sizes ranged from 1.7-1.8 Gy for craniospinal fields and 2 Gy for the posterior fossa boost. Seventy percent completed the prescribed course within 7 weeks.
Results: Actuarial survival for the whole group of 149 patients was 53% at 5 years and 38% at 10 years. On univariate analysis, patients with T2 tumors did significantly better as compared to patients with T3 and T4 tumors. Survival of patients who had clinical and radiological complete resection of tumor at surgery was significantly better than patients with incomplete tumor removal. The presence of a ventriculoperitoneal (VP) shunt had a significant negative impact on survival. Treatment failure by site was analyzed with respect to the radiation dose. Doses greater than 50 Gy for the posterior fossa, and greater than 30 Gy for craniospinal axis, resulted in significantly better survival. On multivariate analysis, the only significant prognostic factor was the presence of a VP shunt in patients with T2 tumors.
Conclusion: T stage, VP shunt, radiation doses and extent of surgery were important prognostic factors. In this study, radiation doses of more than 50 Gy to the posterior fossa and 30 Gy to the craniospinal axis resulted in improved survival.