REDUCED-DOSE CRANIOSPINAL IRRADIATION IS FEASIBLE FOR STANDARD-RISK ADULT MEDULLOBLASTOMA PATIENTS
Introduction. Medulloblastoma is the most common malignant brain tumor in children, but
accounts for only 1% of brain cancers in adults. For standard-risk pediatric medulloblastoma,
current therapy includes craniospinal irradiation (CSI) at reduced doses (23.4 Gy) associated with
chemotherapy. Whereas most same-stage adult patients are still given CSI at 36 Gy, with or
without chemotherapy, we report here on our use of reduced-dose CSI associated with
chemotherapy for older patients. Methods. We gathered non-metastatic patients over 18 years
old (median age 28 years, range 18-48) with minimal or no residual disease after surgery, no
negative histological subtypes, treated between 1996-2018 at the Centre Léon Bérard (Lyon) and
the INT (Milano). A series of 54 children with similar tumors treated in Milano was used for
comparison. Results. Forty-four adults were considered (median follow-up 101 months): 36 had
23.4 Gy of CSI, and 8 had 30.6 Gy, plus a boost to the posterior fossa/tumor bed; 43 had
chemotherapy as all 54 children, who had a median 83-month follow-up. The PFS and OS were
82.2 ± 6.1% and 89 ± 5.2% at five years, and 78.5 ± 6.9% and 75.2 ± 7.8% at ten, not significantly
different from those of the children. CSI doses higher than 23.4 Gy did not influence PFS. Female
adult patients tended to have a better outcome than males. Conclusion. The results obtained in
our combined series are comparable with, or even better than those obtained after high CSI doses,
underscoring the need to reconsider this treatment in adults.