Pattern of recurrence of medulloblastoma after low-dose craniospinal radiotherapy

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    21-Jun-2016

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  • Proceedings of the 35th Annual ASTRO Meeting 133

    Results: Median follow-,up was 48 months. Poor-risk patients had a 5 year disease-free survival (DFS) of 35% vs. 60% for good- risk. 5 year overall survival (OS) was 57%; 46% for poor-risk vs. 72% vs. good-risk patients. Treatment of poor-risk patients with low-dose or high-dose CSRT resulted in 23% vs. 32% DFS. Good-risk patients treated with low-dose or high-dose CSRT had a 40% vs. 62% DFS, respectively. Although, the high-dose CSRT regime contained a greater percentage of patients with poor-risk disease, high-dose CSRT yielded a 55% 5 year DFS vs. 36% for the low-dose group. There are a high number of failures in the posterior fossa despite boosts to 54 Ciy. Late sequelae were increased in the high-dose CSRT group.

    FAILURE BY SITE: GOOD-RISK FAILURES POOR-RISK FAILURES ??O Gy CSA >30 Gy CSA 30 Gy CSA

    posterior fossa 3 3 5 5 brain 1 brain + pf : : : cord 0 z 3 mets :. 1 0 3 other,*2 dead from sepsis

    Conclusions: Low-dose craniospinal radiotherapy is associated with an increased risk of failure outside of the primary high-dose area. Recommendations, now are for a return to 35-40 Gy to prophylactic areas and high dose, 60-72 Gy, to the primary area to further increase disease-free survival for medulloblastoma.

    11 THE EFFECT OF PRE-I;X&QIATION CHEMOTHERAPY ON THE DELIVERY OF RADIATION THERAPY FOR MEDULLOBIASTOMA AND SUPRATENTORIAL PNET. RESULTS OF THE CCG #921 RANDOMIZED PROTOCOL

    Stevens, K.R., Jr., Cherlow, J.. Zeltzer, P., Finlay, J., Geyer, .J., McGuire, P., Milstein,

    Boyett, J., Ayers, IJ , Shurin, S., Albright, A., Allen, J., J., Rorke, L., Starlie:: ?., Stehbens, J., Wisoff, J.

    Childrens Cancer Group, Arcadia, CA

    Purpose: This prospective randomized study (5/86 through 6/92) compared pre/post standard irradiation "8 drugs in 1 day" chemotherapy to standard irradiation and vincristine, CCNU, prednisone in 298 children with advanced stage medulloblastoma or supratentorial PNET. The purpose of this review is to: (1) present the preliminary results of this study, (2) discuss the effect of the chemotherapy regimens on the delivery of radiation therapy (delay in starting and overall treatment-time of radiation therapy) and (3) assess the quality of the administered radiation and its effect on patient outcome.

    Materials/Methods: For children older than 3 years, the protocol-specified radiation dose was 54 Gy (1.8 Gy/fraction. 5 fractions/week) to the primary tumor and 36 Gy to the crania-spinal axis. For children between the ages of 18 and 36 months, the radiation dose was 45 Gy to the primary tumor and 23.4 Gy to the crania-spinal axis. Metastatic tumor deposits identified at the time of original diagnosis received additional irradiation. There was central review of radiation treatment records and port films.

    Results: Three-year overall survival and progression-free survival for children with these advanced stage tumors are 66%(+4%) and 57%(24%). With a median follow-up of 3 years, there is no statistical difference in survival between the two chemotherapy regimens. Toxicities were primarily hematologic. The mean delay in starting radiation therapy per protocol was 0 for standard therapy and 7 days for children treated with 8- in-one. There was no evidence of clinically significant difference in overall duration of radiation therapy treatment time between the two chemotherapy regimens. The duration of the radiation therapy course was within lOO-105% of the specified protocol treatment time for 66% of patients. Fifteen per cent of patients had overall treatment time greater than 125% of the protocol-specified time. Central radiation therapy review: Potential tumor volume was identified as being shielded in the primary tumor field-2%, whole brain field-5%. and spinal field-l% of children. Only two to four percent of children received 95% of patients receiving >95% of protocol-specified dose with satisfactory treatment volumes.

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