ESTRO 2023 - Abstract Book

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ESTRO 2023

From 1/2018 to 7/2022, 161 lesions in 42 patients (pts) were re-irradiated with robotic SRT (Cyberknife®, CK). Primary tumor was NSCLS for 13 pts, breast cancer for 12, glioblastoma for 5, meningioma for 3, melanoma for 2, hemangiopericytoma for 2, oligodendroglioma for 2, pituitary adenoma for 2, prostate cancer for 1 patient. Previous RT on the same volume was performed with: Gamma Knife in 10 pts, whole-brain RT in 10, CK in 10, post-operative IMRT in 5, VMAT SRT in 4, and post-operative 3D-CRT in 3 pts. Median time from previous RT was 13 (3-378) months. Eight pts had ≥ 2 previous treatments. Median GTV was 6.9 (0.02-78.32) cc. Median PTV was 12 (0.07-136.9) cc. Median prescribed dose was 30 (21-35) Gy in 1-5 fractions, at a median isodose of 70 (69-80)%. Prophylactic corticosteroid therapy was prescribed to all pts. Post-treatment MRI was used to assess response to re-irradiation. Survival curves were calculated from the date of treatment by using the Kaplan-Meier (KM) method. Results Median follow-up after re-irradiation was 10 (2.8-39.7) months. SRT was delivered on a median number of 1 (1-24) lesions; 8 pts were treated on >5 lesions simultaneously (from 6 to 24 lesions). Acute toxicity was G2 headache in 3 pts: (with GTV >1cc or >3 lesions), treated by increasing the dose of corticosteroids. Radionecrosis occurred in 3 pts: 1 patient (GTV 1.38 cc) underwent 2 previous VMAT SRT and presented seizures, 1 patient (GTV 0.49 cc) underwent 1 previous VMAT SRT and presented headache and 1 patient (GTV 5.54 cc) underwent previous GK and CK and was asymptomatic. Maximal local response, evaluable in 35 pts, was: complete response (RC) in 2 patients, partial response (PR) in 20 pts, stable disease (SD) in 7 pts and progressive disease (PD) in 6 pts. Six-, 12- and 18 month overall survival were 76.9%, 51.8% and 34.2% (see Fig.1). Six-, 12- and 18 month local relapse-free survival (LRFS), evaluable in 32 pts, were 70.9%, 55.6%, 55.6%.

Fig.1: Six-, 12- and 18 month overall survival

Conclusion SRT re-irradiation of brain recurrent disease is effective with responses in 83% of pts. Accurate patient selection is warranted in order to avoid toxicity and a longer follow-up is needed to confirm these results.

PO-1130 Long-term outcomes for NSCLC patients with brain metastases treated with SRS or SRT

I. Chiovatero 1 , A. Gastino 1 , I. Bonavero 1 , G. De Giorgi 1 , E. Cuffini 1 , C. Casale 1 , M. Cerrato 1 , L. Blasi 1 , S. Badellino 1 , C. Mantovani 1 , U. Ricardi 1 , M. Levis 1

1 University of Turin, Department of Oncology, Torino, Italy

Purpose or Objective To evaluate long-term results of a cohort of patients with brain metastases (BMs) from non-small cell lung cancer (NSCLC), treated with radiosurgery (SRS) or fractionated stereotactic radiotherapy alone or combined with whole-brain radiotherapy (WBRT). Materials and Methods We retrospectively analyzed the data of all consecutive patients treated with SRS or fractionated stereotactic radiotherapy for BMs at our Institution between January 2010 and December 2020. Local control (LC) of treated lesions and overall survival (OS) were estimated using the Kaplan-Meier method. Chi-squared test was used to examine between-group covariate differences, and the Cox proportional hazards model was used for univariate and multivariate analysis to assess the effects of clinical/treatment variables on clinical outcomes. Results Overall, we treated 533 lesions in 354 patients. The median age was 65 years (range 36-88 years) and 214 were male (60.5%). Predominant stage disease at diagnosis was metastatic (176 patients, 49.7%) of which 159 (44.9%) were oligometastatic. 272 patients (76.8%) had only supratentorial BMs, 50 (14.1%) patients had only infratentorial BMs, while 32 (9%) remaining patients had both supratentorial and infratentorial BMs. The median overall treated volume was 2.762 cc (range 0.14-84.673 cc). 154 patients (43.5%) were on corticosteroid treatment (CST) for neurological symptoms before SRS and 264 patients had a KPS > 80 (74.6%). Concomitant or sequential WBRT was given to 45 patients (12.7%). Adjuvant SRS to the surgical cavity of a resected BMs was performed in 39 patients (Table 1). With a median follow up of 15 months, we observed 1-yr LC and OS of 87% and 62%, respectively. After multivariate analysis we observed a lower LC for lesions treated with a dose ≤ 18 Gy (HR: 3.830, p<0,001), while for patients underwent concomitant systemic therapy during SRS we found a better LC (HR: 0.296, p<0,001). The need of CST before SRS (HR: 1.770, p<0.001), having >1 BM before SRS (HR: 1.349, p=0.020), an overall metastatic treated volume > 3 cc (HR: 1.457,