ESTRO 2023 - Abstract Book

S917

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ESTRO 2023

Conclusion Both fGK and helical IMRT/VMAT ensured good results in terms of PFS, local control and acute toxicity. Late toxicity was slightly worse in the helical IMRT/VMAT group, due to the higher volume treated. Higher PTV volume, BED3 and male gender negatively correlated with OS.

PO-1147 Hypofractionated and Intensified Radiotherapy for nonsurgical Glioblastoma Multiforme

&. Nieto Regueira 1 , B. Vázquez Barreiro 2 , V. Ochagavia Galilea 1 , V. Muñoz Garzón 1

1 Hospital Meixoeiro. Complejo Hospitalario Universitario de Vigo, Radiation Oncology, Vigo, Spain; 2 Hospital Meixoeiro. Complejo Hospitalario Universitario de Vigo, Radiation Oncology , Vigo, Spain Purpose or Objective INTRODUCTION Glioblastoma Multiforme (GM) still has a poor prognosis. The association of surgery , adjuvant Radiotherapy and concurrent Temozolomide is the standard treatment. The median overall survival, is 14.6 months according to Stupp trial. If the predicted postoperative morbidity and mortality are high, surgery is contraindicated. and Radiotherapy is then, the first treatment option. In these cases of biopsied patients, overall survival is considerably reduced. Conventional RT dose is 60 Gy total dose, 2 Gy per day. Our porpuse es to analize the tolerance and overall survival(OS) in patients with nonsurgical Glioblastoma Multiforme, (biopsied patients) treated with Hypofractionated and Intensified Radiotherapy (HIRT), in a phase II prospective trial. Materials and Methods Between January 2016 and December 2021 we have treated 51 nonsurgical GM patients, 34 men (67%) and 17 women (33%) with Hypofractionated and Intensified RT. Median age was 60.1 (31-83 years old). All of them received IMRT, in 20-25 fractions, (24.5 median fractions) in a dose escalated phase II trial, from a total dose of 66 Gy, to 79.65 Gy (median 69.8 Gy) EQD2 86 Gy), as follows:

PTV1 : 50 Gy in 2 Gy per fraction. PTV2 , as a concurrent boost receiving up to 79.65 Gy . 2.2 – 3.16 Gy per fraction.

40 patients received concurrent Temozolomide, 25 patients of them received at least three adjuvant Temozolomide cycles . Organs at risk were delimited: Braim stem, chiasm and optical nerves, motor cortex, pyramidal path, pituitary, hippocampus and cerebrum. After treatment, follow-up was done every 3 month with MRI .

We have analyzed survival in two groups, depending on the fractionation: <2.5 and ≥ 2.5 Gy