ESTRO 2024 - Abstract Book

S890

Clinical - CNS

ESTRO 2024

studies or at least studies with large numbers for re-irradiation. Here we present the results of salvage Stereotactic Radiotherapy (SRT)/Radiosurgery (RS) for the treatment of recurrent BM after previous radiotherapy (RT)

Material/Methods:

From January 2018 to July 2022, 134 BM in 32 cases were re-irradiated. Median re-irradiated BM per patient was 2 (1-21). Median age re-irradiation was 56.1 (40.9-70.7) years. The most frequent primary tumors were: lung cancer for 53.1% of cases, breast cancer for 34.4%, and melanoma for 6.3% of cases. Time interval between first BM RT and ReRT was 14 (4.2-39.2 months). Previous RT on the same volume was performed as whole-brain radiotherapy (WBRT) in 46.9 % of patients (in 6.3% a simultaneous integrated boost was delivered), CyberKnife SRT (CK) in 21.9%, Volumetric Modulated Arc Therapy SRT (VMAT) in 15.6 %, Gamma Knife RS (GK) in 12.5%, and tumor bed irradiation in 3.13%. Median dose delivered was 30 (20-50) Gy in 1-25 fractions. ReRT was performed with CK in 23 patients, GK in 8, and TomoTherapy in one patient. Median re-irradiated volume (PTV) was 3.45 (0.3-31.76) cc. Median dose prescribed was 30 (17-37.5) Gy in a median of 5 (1-5) fractions, at the 77 (50-95)% isodose. Prophylactic corticosteroid therapy was prescribed for 28 patients. Common Toxicity Criteria For Adverse Events (CTCAE) v 5.0 was used to report toxicity.

Results:

Median follow-up after re-irradiation was 10 (1-54.4) months. Although 11 patients were re-irradiated in a single treatment on ≥3 BM, and in 14 patients the re - irradiated volume was ≥ 4 cc, acute toxicity was low: 71.0% of patients did not present any toxicity, 22.5% a G1 toxicity, and 6.5% a G2 toxicity. Acute toxicity registered were headache in 7 patients, headache, nausea and confusion in one patient and dysgeusia in one patient. Acute toxicity was more frequent in treatments performed in one fraction (44.4%), than in fractionated treatments (22.0%). Six radionecrosis were registered during follow-up in patients who survived more than 13 months. Local control, evaluable in 30 pts, was: complete response (RC) in 4 patients, partial response (PR) in 16, stable disease (SD) in 6 and progressive disease (PD) in 4 patients. Twelve patients presented a relapse or progressive disease of the retreated BM, and 15 patients an intracranic progression. Eleven patients died for intracranic PD, one for local PD, one for local and intracranic, one for intracranic and systemic PD, 8 for systemic PD and 2 for other reasons. Three patients receive a second re-irradiation. Median overall survival was 10 months, 12, 24- and 36-month OS were 39.1%, 24.8%, and 18.6%, respectively. Median local progression-free survival was 22 months, 6-, 12-, 24- and 36 month LPFS were 79.8%, 60.1%, 36.1% and 36.1%, respectively (see Fig. 1). Median intracranial progression-free survival was 10.1 months, 6-, 12-, 24- and 36-month ICPFS were 63%, 40.8%, 28%, and 28%, respectively. Initial WBRT did not reduce intracranial progression at either the first or second event (p=0.14 and 0.13, respectively)