Hyperfractionated craniospinal re-irradiation for recurrent/progressive disseminated medulloblastoma using image-guided radiotherapy: leveraging radiobiology with technology

Abstract

Medulloblastoma, the most common primary malignant central nervous system tumor of childhood has a high propensity to spread along cerebrospinal fluid pathways. Craniospinal irradiation, therefore, remains an integral component of post-operative adjuvant treatment, even without clinicoradiological evidence of leptomeningeal metastases. Despite newer insights in molecular biology and significant advances in treatment of medulloblastoma, the prognosis of previously irradiated recurrent/progressive disease remains dismal with few long-term survivors. Leptomeningeal dissemination is the predominant pattern of relapse following curative-intent treatment that is generally not amenable to any salvage therapy including high-dose chemotherapy with stem cell rescue. Re-irradiation of the entire craniospinal axis for recurrent/progressive disseminated medulloblastoma is seldom considered feasible owing to its potential toxicity, young patient population, and uncertain efficacy. Important factors for consideration should include age at re-irradiation, prior doses of radiation, interval since first course of radiotherapy, and cumulative doses of radiotherapy. We present a case report of hyperfractionated craniospinal re-irradiation using image-guided intensity modulated radiation therapy on helical tomotherapy for progressive disseminated medulloblastoma with limited acute toxicity, encouraging early response, disease stabilization, and no significant late toxicity and discuss how leveraging radiobiology with technology may help minimize toxicity while maintaining efficacy to optimize the therapeutic index of re-irradiation.