ESTRO 2023 - Abstract Book

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ESTRO 2023

Materials and Methods Between January 2015 and June 2022, 32 consecutive patients with recurrent meningioma were re-irradiated with active scanning PT at our institution. Treatment planning was generated with active beam scanning PT using 3-4 fields with single or multiple field optimization technique. Prescription dose ranged from 50.4 to 60 GyRBE (RBE: relative biologic effectiveness), with a median dose of 54 GyRBE in 30 fractions. Biologically equivalent doses in 2 Gy fractions (EQD2) for normal tissue and tumor were estimated for each previous course (a/b =2 for brain tissue and a/b = 4 for meningioma), as well as biological effective dose (BED). Median age and KPS at re-irradiation were 61 years (range 34-89) and 90, (range 60– 100), respectively. The four patients (12.5%) who had no histologic sampling were grouped with the grade I patients for further analysis (13%). Median time from prior RT to reirradiation was 66 months (range 4-288 months) and median GTV was 43 cc (range 1.2-225.5 cc). Results At the median follow-up was 27 months (range 1-72 months) median, 1-yr and 2-yr PFS were 23.6 months, 89.4% and 74.5%, respectively (fig.1). Histology showed a trend toward a significant impact on PFS (p: 0.06); median and 2-yr PFS were 32.5 months and 100% for grade I, 25.6 months and 76% for grade II, 16.6 months and 50% for grade III, respectively. Median, 1 yr and 2-yr OS were 30 months, 86% and 83%, respectively. At last follow-up the rate of local recurrence was 34% (eleven patients) and we registered 6 meningioma-related deaths (18.5%). Median time of recurrence was 13.4 months (range 6.1 26.3 months). The treatment was well tolerated with mild symptoms; no registered acute grade 3 or higher toxicities were reported except a case of grade 3 erythema and a case of grade 3 hydrocephalus that needed ventriculoperitoneal drain after three months the end of PT. As well, late toxicity was limited to grade 2 or less. Five patients (15%) developed radionecrosis (RN) with a median time of 3.4 months from the end of PT (range 3-8.8 months) and with a median time from prior RT to reirradiation of 29.5 months (range 12.5-45.6 months). Interestingly, a cumulative EQD2 tumor dose > 98.1 GyRBE seems to be associated with a significant increased risk of RN (p: 0.02); no cumulative EQD2 brain tumor dose showed a significant correlation with the occurrence of RN. Conclusion Re-irradiation with PT of meningiomas progressing after previous RT appears to be feasible with promising clinical outcomes and an acceptable toxicity profile. Longer follow-up and prospective trials are necessary to assess definitive efficacy and provide strong evidence of particle therapy in the contest of re-irradiation for recurrent meningioma. 1 University Hospital Amiens, Radiotherapy, Amiens, France; 2 Oscar Lambret Center, Radiotherapy, Lille, France; 3 University Hospital of Marseille La Timone, Radiotherapy, Marseille, France; 4 University Hospital of Amiens, Radiology, Amiens, France; 5 University Hospital of Amiens, Nuclear Medicine , Amiens, France; 6 University Hospital of Amiens, Radiotherapy, Amiens, France; 7 University Hospital of Amiens, Neurosurgery, Amiens, France (PA) treatment. Radiation therapy is indicated as a treatment for residual or recurrent pituitary adenomas after surgery, in order to reduce hormonal or visual symptoms related to the adenoma progression. Conventional radiation therapy (CRT) is indicated for tumors of any and Radiosurgery (SRS) is mainly indicated for PA <3cm and located more than 2mm away for the optic pathways. The role of hypofractionated stereotactic radiotherapy (HFSRT) for the treatment of these tumors is unclear. The aim of this study is to compare HFSRT to CRT in terms of efficacy (local control, hormonal normalization, visual control) and safety (toxicities, visual deterioration, new hypopituitarism). Materials and Methods We retrospectively analyzed data from patients treated with radiotherapy for pituitary adenoma at the University Hospital of Amiens and Marseille between 2011 and 2020. 38 patients were treated with HFSRT with the Cyberknife, and 38 patients were treated with CRT with Intensity Modulated Radiotherapy. For HFSRT, 3 x7 Gy, or 5x5 Gy were prescribed for nonfunctioning adenomas whereas 3 x10-12 Gy for secretory adenomas. For CRT, 26 to 30 fractions of 1,8-2 Gy were used. are mostly treated by surgery or medical Purpose or Objective Pituitary adenomas PO-1139 Effectiveness and safety of Hypofractionated Stereotactic Radiotherapy in pituitary adenomas V. Delgrange 1 , C. Beaudelot 2 , L. Padovani 3 , N. Deleval 4 , E. Marchal 5 , R. Fabbro 6 , A. Laville 6 , A. Coutte 6 , M. Lefranc 7

Results The clinical characteristics of the population are shown in the table 1.