Hyperfractionated craniospinal radiotherapy and adjuvant chemotherapy for children with newly diagnosed medulloblastoma and other primitive neuroectodermal tumors.

PURPOSE

This single-institution Phase III study conducted from 1989 to 1995 evaluates the feasibility of a multimodality protocol combining hyperfractionated craniospinal radiotherapy (HFRT) followed by adjuvant chemotherapy in 23 patients with newly diagnosed primitive neuroectodermal tumors (PNET) arising in the central nervous system.

METHODS AND MATERIALS

All 23 patients had a histologically confirmed PNET and were over 3 years of age at diagnosis. The eligibility criteria for PNET patients with cerebellar primaries (medulloblastoma) included either a high T stage (T3b or 4) or high M stage (M1-3). All patients with noncerebellar primaries were eligible regardless of T or M stage. The median age of the 23 patients was 9 years (mean 3-25); 11 were female. The primary tumor arose in the cerebellum in 19. Of these medulloblastoma patients, 15 had high T stages (T3b or T4) with large locally invasive tumors and no evidence of metastases (M0), constituting Group 1. Thirteen (86%) of these patients had gross total resections. Four other medulloblastoma patients had both high T and high M stages, constituting Group 2. Group 3 consisted of four other patients with exocerebellar primaries (two brain, one brain stem, and one cauda equina), three of whom were M3. Hyperfractionated radiotherapy was administered within 4 weeks of surgery. Twice-daily 1-Gy fractions were administered separated by 4-6 h. The total dose to the primary intracranial tumor and other areas of measurable intracranial disease was 72 Gy. The prophylactic craniospinal axis dose was 36 Gy, and boosts of 44-56 Gy were administered to metastatic spinal deposits. Following radiotherapy, monthly courses of multiagent chemotherapy were administered sequentially (cyclophosphamide-vincristine followed by cisplatin-etoposide followed by carboplatin-vincristine) for a total of 9 months.

RESULTS

All patients completed radiotherapy as planned. Only three patients lost >10% of their body weight. One patient had clinically apparent radiation-induced esophagitis. The mean white blood count (WBC) nadir was 2.5/dl, and hematologic recovery occurred in all within 4 weeks of completing HFRT without the need of granulocyte-colony-stimulating factor. Two patients refused adjuvant chemotherapy, 3 patients experienced tumor progression during chemotherapy, and 2 of 18 remaining patients could not tolerate the full 9 months owing to hematologic toxicity. Of the 15 patients (93%) in Group 1, 14 remain in continuous remission for a median of 78 months, and none have died. Two of four patients in Group 2 are in continuous remission at 67 and 35 months, and two died at 18 and 30 months. One of the two patients in Group 2 who died refused adjuvant chemotherapy and developed tumor progression in the bone marrow. None of the three patients in Group 3 with evaluable disease (M3) had a complete response to therapy, and eventually all four died of progressive or recurrent disease.

CONCLUSION

This multimodality protocol is feasible in the short term, and long-term monitoring of neurocognitive and neuroendocrine effects are in progress. Excellent long-term disease control has been achieved for medulloblastoma patients with high T stages who were M0 at diagnosis (Group 1), the majority of whom had gross total resections. This group has a progression-free survival of 95% after a median period of follow-up of 6.5 years. Alternative treatment strategies must be developed for patients with high M stages, as five of seven patients died of progressive or recurrent disease.