The efficacy of adjuvant chemotherapy for patients with poor-risk medulloblastoma/primitive neuroectodermal tumors (MB/PNET) has been studied at the Children’s Hospital of Philadelphia, University of Pennsylvania, PA. Chemotherapy consisted of vincristine during concomitant craniospinal radiation therapy and eight 6-week cycles of vincristine, cis-platinum, and cyclohexylnitrosourea. Twenty five of 26 children (96%) treated remain alive and free of disease at a median of 24 months from diagnosis (range 6-50 mos). Actuarial disease-free survival was statistically significantly better than for control subjects who had received radiation therapy alone during an 8 year period prior to the use of adjuvant chemotherapy. The 2-year disease-free survival was 96% for patients on the protocol of adjuvant chemotherapy as compared to 59% for historical control patients treated with radiotherapy alone. 
COMMENT. Surgical excision for the treatment of medulloblastoma has less than a 6 month survival rate, and postoperative radiation of the tumor bed alone has minimal benefit. Irradiation of the tumor bed and the entire neuroaxis provides an overall chance of 30% to 50% for 5 year survival. Patients with clinical evidence of arachnoidal seeding or with gross evidence of seeding at surgery do poorly. Survival without evidence of recurrent tumor for a period exceeding the patient’s age at diagnosis plus 9 months indicates a probably cure (“Collins’ law“). Corticosteroids result in remarkable amelioration of root signs and symptoms and reduction of edema for a brief period. Experience with chemotherapy in the past 25 years has produced better survival rates, and used as an adjuvant these agents are indicated for the poor-risk patients, that is, those less than 5 years of age at diagnosis or with disseminated tumors (Chang stages Ml - M3).