Multi-Institution Prospective Trial of Reduced-Dose Craniospinal Irradiation (23.4 Gy) Followed by Conformal Posterior Fossa (36 Gy) and Primary Site Irradiation (55.8 Gy) and Dose-Intensive Chemotherapy for Average-Risk Medulloblastoma

• Published in: International journal of radiation oncology, biology, physics Vol. 70; no. 3; pp. 782 - 787
• Main Authors: Merchant, Thomas E., D.O., Ph.D, Kun, Larry E., M.D, Krasin, Matthew J., M.D, Wallace, Dana, M.S, Chintagumpala, Murali M., M.D, Woo, Shiao Y., M.D, Ashley, David M., M.B.B.S, Sexton, Maree, M.B.B.S, Kellie, Stewart J., M.B.B.S, Ahern, Verity, M.B.B.S, Gajjar, Amar, M.D
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2008
• Subjects: Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; CARCINOMAS; Central nervous system neoplasm; Cerebellar Neoplasms - drug therapy; Cerebellar Neoplasms - radiotherapy; CHEMOTHERAPY; Child; Child, Preschool; Cisplatin - administration & dosage; Cognition Disorders - prevention & control; Combined Modality Therapy - methods; Conformal radiotherapy; Cyclophosphamide - administration & dosage; Disease-Free Survival; ENDOXAN; FAILURES; Female; HEALTH HAZARDS; Hematology, Oncology and Palliative Medicine; Humans; HYPOTHALAMUS; Infratentorial Neoplasms - drug therapy; Infratentorial Neoplasms - radiotherapy; IRRADIATION; Male; Medulloblastoma - drug therapy; Medulloblastoma - radiotherapy; PEDIATRICS; Prospective Studies; RADIATION DOSES; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; RADIOTHERAPY; Radiotherapy Dosage; Radiotherapy, Conformal - methods; RECOMMENDATIONS; SURGERY; Tumor Burden; Vincristine - administration & dosage; Conformal radiotherapy; Pediatrics; Central nervous system neoplasm; Chemotherapy; Radiotherapy
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2007.07.2342

Purpose Limiting the neurocognitive sequelae of radiotherapy (RT) has been an objective in the treatment of medulloblastoma. Conformal RT to less than the entire posterior fossa (PF) after craniospinal irradiation might reduce neurocognitive sequelae and requires evaluation. Methods and Materials Between October 1996 and August 2003, 86 patients, 3–21 years of age, with newly diagnosed, average-risk medulloblastoma were treated in a prospective, institutional review board–approved, multi-institution trial of risk-adapted RT and dose-intensive chemotherapy. RT began within 28 days of definitive surgery and consisted of craniospinal irradiation (23.4 Gy), conformal PF RT (36.0 Gy), and primary site RT (55.8 Gy). The planning target volume for the primary site included the postoperative tumor bed surrounded by an anatomically confined margin of 2 cm that was then expanded with a geometric margin of 0.3–0.5 cm. Chemotherapy was initiated 6 weeks after RT and included four cycles of high-dose cyclophosphamide, cisplatin, and vincristine. Results At a median follow-up of 61.2 months (range, 5.2–115.0 months), the estimated 5-year event-free survival and cumulative incidence of PF failure rate was 83.0% ± 5.3% and 4.9% ± 2.4% (± standard error), respectively. The targeting guidelines used in this study resulted in a mean reduction of 13% in the volume of the PF receiving doses >55 Gy compared with conventionally planned RT. The reductions in the dose to the temporal lobes, cochleae, and hypothalamus were statistically significant. Conclusion This prospective trial has demonstrated that irradiation of less than the entire PF after 23.4 Gy craniospinal irradiation for average-risk medulloblastoma results in disease control comparable to that after treatment of the entire PF.