ESTRO 2022 - Abstract Book

S989

Abstract book

ESTRO 2022

A total of 20 patients were available for analysis (median age 15 years). Out of this, 13 and 7 patients were treated with 3DCRT and VMAT respectively. Seven patients experienced treatment interruption due to hematological toxicity. Details of hematological toxicity and treatment interruption is shown in Table 1. In VMAT group, 5 out of 7 (71.4%) patients had at- least grade 2 hematological toxicity as compared to only 2 out of 13 (15.4%) patients in 3DCRT group. Majority of the patients experiencing hematological toxicities were below 14 years of age. Most of the treatment interruptions were started in the 2 nd week of CSI. The incidence of hematological toxicity was significantly associated with bone marrow volume receiving low dose radiation, particularly 3 and 5 Gy (p-0.04). Figure 1 is showing dose colour wash of bone marrow volume receiving (A) 3 Gy in 3DCRT group; (B) 3 Gy in VMAT group (C) 5 Gy in 3DCRT group and (D) 5 Gy in VMAT group. No significant association of hematological toxicity was found with the age or baseline blood counts. Conclusion There is no substantial evidence to suggest excess bone marrow suppression in medulloblastoma patients treated by VMAT as compared to 3DCRT. Higher incidence of hematological toxicity in the index study, in the VMAT group, can be explained by the high bone marrow volume exposing to low dose radiation. Though the results from our study cannot be generalized due to small sample size and selection bias, VMAT should be used carefully after considering bone marrow sparing in the treatment plan optimization to reduce the incidence and severity of hematological toxicity.

PO-1167 Re-irradiation in glioblastoma: is it possible? Is it feasible?

A. Surgo 1 , F. Gregucci 2 , L. Laera 3 , R. Carbonara 4 , M.P. Ciliberti 1 , M. Caliandro 4 , I. Bonaparte 4 , A. Fiorentino 1

1 General Regional Hospital "F. Miulli", Radiation Oncology Department, Acquaviva delle Fonti (BA), Italy; 2 General Regional Hospital “F.Miulli” , Radiation Oncology Department, Acquaviva delle Fonti (BA), Italy; 3 General Regional Hospital “F.Miulli”, Medical Oncology Department, Acquaviva delle Fonti (BA), Italy; 4 General Regional Hospital "F. Miulli" , Radiation Oncology Department, Acquaviva delle Fonti (BA), Italy

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