Online quality control, hyperfractionated radiotherapy alone and reduced boost volume for standard risk medulloblastoma: long-term results of MSFOP 98

Abstract

Purpose: To determine event free and overall survival, and long-term cognitive sequelae of children with standard-risk medulloblastoma (SRM) treated with hyperfractionated radiotherapy, conformal reduced boost volume without chemotherapy, and online quality assurance.

Patients and methods: Forty-eight patients (age 5 to 18 years) were included in the Medulloblastoma-Société Française d'Oncologie Pédiatrique (MSFOP 98) protocol (December 1998 to October 2001). Patients received hyperfractionated radiotherapy (HFRT; 36 Gy, 1 Gy/fraction twice per day) to the craniospinal axis followed by a boost to the tumor bed (1.5-cm margin) to a dose of 68 Gy. Records of craniospinal irradiation were reviewed before treatment started. Neuropsychologic evaluations were done according to the protocol (1, 3, 5, and 7 years after irradiation). Cognitive outcomes were followed longitudinally with full-scale intelligence quotient (FSIQ) obtained with age-adapted Wechsler scales.

Results: After a median follow-up of 77.7 months, 6-year overall survival (OS) and event-free survival (EFS) rates for the cohort were 78% (95% CI, 66% to 90%) and 75%, respectively (95% CI, 62% to 87%). Thanks to quality control, 14 major deviations were detected. Annual full scale IQ decline was 2 points over a 6-year period. Predicted change in FSIQ points per year was 2.15 (95% CI, -1.24 to 3.51) with an intercept (ie, predicted FSIQ) of 93.57 at baseline.

Conclusion: HFRT protocol with conformal reduced boost and online quality control allows excellent long-term OS and EFS in the absence of chemotherapy. In addition, FSIQ drops seem to be less pronounced than previously reported with standard irradiation regimens.