ESTRO 2023 - Abstract Book

S892

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ESTRO 2023

Conclusion Conclusions

In our experience, single isocenter SRS for multiple brain metastases planned with dynamic conformal arc therapy generates treatment plans with adequate dose gradients and optimum healthy brain sparing.

PO-1115 Proton therapy re-irradiation plus chemotherapy achieves promising results in recurrent glioblastoma

D. Amelio 1 , R. Pertile 2 , S. Brugnara 3 , S. Vennarini 4 , I. Giacomelli 5 , F. Chierichetti 6 , P. Feraco 7 , S. Sarubbo 8 , F. Valent 2 , D. Scartoni 5 1 Proton Therapy Center , Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy; 2 Clinical Epidemiology Unit, Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy; 3 Medical Oncology Department, Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy; 4 Radiotherapy Department, Fondazione IRCCS Istituto Nazionale Tumori , Milano, Italy; 5 Proton Therapy Center, Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy; 6 Nuclear Medicine Department, Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy; 7 Radiology Department, Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy; 8 Neurosurgery Department, Azienda Provinciale per i Servizi Sanitari Trento, Trento, Italy Purpose or Objective To report the results of re-irradiation with proton therapy (PT) with or without chemotherapy (CHT) in difficult-to-treat recurrent glioblastoma (rGBM) patients (pts) Materials and Methods Between January 2015 and January 2022 fifty-four pts with rGBM were re-irradiated with PT. All pts had been previously treated with Stupp regimen. Twenty-eight (52%) were re-irradiated at first relapse/progression, twenty-six at the second/third one. Fifteen pts (28%) were re-irradiated after partial tumor resection. Median age and Karnofsky performance status at re-irradiation were 54 years and 80%, respectively. Median time between prior radiotherapy and PT was 16 months. Target definition was based on CT, MR, and amino acid PET imaging. Median CTV volume was 54 cc (range, 8-185 cc). All pts received 36 GyRBE in 18 fractions. PT was delivered with or without CHT as follows: 24 (44%) pts (Group 1) received PT only; 7 (13%) pts (Group 2) also received concomitant TMZ (75 mg/m2/die, 7 days/week); 19 (35%) pts (Group 3) received PT followed by CHT (different regimens/drugs); 4 (8%) pts (Group 4) also received concomitant (as above) and adjuvant TMZ (150-200 mg/m2/die, 5 days/month). All pts were treated with active pencil beam scanning PT. Side effects were graded according to CTCAE. Health-related quality of life (HRQOL) was assessed by EORTC QLQ-C30 and QLQ-BN20. OS and PFS after re-irradiation were calculated using the Kaplan Meier method Results There were no grade 3 or higher acute toxicities. There were no grade 3 or higher late toxicities. During follow-up five pts (9%) developed grade 2 radionecrosis (diagnosed at imaging). The median PFS was 4 months, while 6-month PFS rate was 28%. The median PFS was 2.5, 7, 5, and 5.5 months for Group 1-2-3-4, respectively. In univariate analysis, secondary GBM (P = 0.02), age < 54 years (P = 0.03), KPS > 80 (P = 0.01), had an effect on PFS. Median OS after PT was 8.5 months. The treatment was consistently associated with improvement or stability in most of the preselected HRQOL domains. Conclusion PT re-irradiation of difficult-to-treat rGBM showed to be feasible and safe even with concomitant and adjuvant chemotherapy administration. PT does not negatively effect on HRQOL, but rather it seems to preserve HRQOL until the time of disease progression. PFS and OS rates are promising. PT in association with chemotherapy seems to achieve better results in comparison with re-irradiation only and could deserve further evaluation in a large pts sample.

PO-1116 stereotactic radiotherapy with helical tomotherapy for brain metastasis

S. D'Alessandro 1 , S. D'Alessandro 2 , G. Ferrera 2 , V. Figlia 2 , A. Spera 2 , G. Mortellaro 2 , D. Cespuglio 2 , G. Craparo 3 , G. Tringali 4 , L. Blasi 5 , E. Greco 2 , F. Cuccia 2