ESTRO 2022 - Abstract Book

S1250

Abstract book

ESTRO 2022

Materials and Methods 58 patients with oligometastatic primary and contiguous vertebral metastasis treated with SBRT for metastatic sites were retrospectively analyzed. All available imaging modalities were utilized. Target volumes were defined according to the International Spine Radiosurgery Consortium consensus. SBRT doses were 1x16 Gy or 1x 18 Gy according to the anatomic localization, extent of gross metastatic tumor and invading structure and dose constraints of neighboring structures. Results The median tumor volume of the metastatic site treated with SBRT was 27.6±11.6 cc. Minimum dose (Dmin), maximum dose (Dmax) and mean dose (Dmean) for entire cohort were 14.18±1.02, 20.99±1.95 and 18.95±3.26, respectively. Spinal cord volume was 4.41±1.65. the maximum dose of spinal cord (Dmax), the dose to 0.35 cc of spinal cord (D0.35), the dose to 10% of the spinal cord (D10%) and the volume of spinal cord receiving 10 Gy (V10) were 11.68±0.85, 8.91±0.93, 8.53±0.87 and 0.14±0.11, respectively. When compared the CTV dosimetry according to SBRT dose there was no significant difference for 1x16 Gy or 1x18 Gy. Also, spinal cord dosimetry was not different for two groups. Half of the patients (29 pts, 50%) had breast cancer, 15 patients (25%) had prostate cancer, 5 patients (8%) had lung cancer and remaining 9 patients (17%) had various (rectum, cervical, gastric etc.) primaries. A total of 64 lesions were treated with SBRT in a total of 58 patients. The SBRT doses were 1x16 Gy in majority of the patients (40 pts, 69%), and eighteen patients (31%) treated with 1x18 Gy. The median follow-up of entire cohort was 12 months (range, 1- 56 months). For the entire cohort, complete response (CR), partial response (PR) and progressed disease (PD) rates were 31%, 59% and 10%, respectively. Local recurrence was seen in ten patients (17%) within median 6 months after SBRT. The 1 and 2 year OS rates were 84% and 65%, respectively, and the 1 and 2 year PFS rates were 73% and 45%, respectively (Figure 2A and 2B). The 1 and 2 year LC rates were 81% and 70%, respectively (Figure 2C). We performed univariate analysis related with OS, PFS and LC. Patients with primary breast histology have better OS than other patients (24.3 vs. 13.9 months, p=0.024). OS (18.7 vs. 38.8 months, p=0.013) and PFS (5.7 vs. 15.9 months, p<0.001) were worse in patients with recurrence ≤ 12 months. No patient experienced ≥ grade 3 acute or late toxicity. 7 patients (12%) had grade 2, 10 had grade 1 toxicities. Conclusion SBRT is a non-invasive treatment method for spinal metastasis. Most of the data of contiguous vertebrae SBRT come from subgroups of spinal SBRT series and no homogenous series exist addressing the safety and toxicity. In this study, we present the efficacy and safety of 16-18 Gy SBRT to contiguous vertebrae. H. Geinitz 1 , E. Silberberger 1 , K. Spiegl 1 , J. Feichtinger 1 , C. Track 1 , E. Weis 1 , C. Venhoda 1 , R. Huppert 1 , E. Bräutigam 1 , B. Aschacher 1 , L. Kocik 1 , N. Karasek 1 , B. Fischerlehner 1 , G. Gruber 1 , D.V. Bihary 1 , M. Erdei 1 , K. Kirchner 1 , G. Zauner-Barbor 1 , M. Ecker 1 , B. Spindelbalker-Renner 1 , R. Adler 1 , P. Thöne 1 , B. Dieplinger 2 1 Ordensklinikum Linz Barmherzige Schwestern, Department of Radiation Oncology, Linz, Austria; 2 Konventhospital Barmherzige Brueder Linz and Ordensklinikum Linz Barmherzige Schwestern, Department of Laboratory Medicine, Linz, Austria Purpose or Objective The rapid evolution of the Covid-19 pandemic demanded an equally rapid response in the form of vaccine development. When SARS-CoV-2 vaccination became available for vulnerable population groups such as oncologic patients in January 2021, little was known about the effects of vaccination during antineoplastic therapies. To meet related concerns and to be able to give advice on individual protective measurements, we offered patients to monitor SARS-CoV-2 binding antibodies and side effects during the course of their radiotherapy (RT) after the first and/or second vaccination. This dataset was analysed retrospectively after approval by the local ethics committee. Materials and Methods Patients attending the department of Radiation Oncology, Ordensklinikum Linz who were scheduled to receive a SARS-CoV- 2 vaccination during (first and/or second dose) or within 6 weeks after RT were offered serial antibody measurements (Elecsys Anti-SARS-CoV-2 S Assay (Roche Diagnostics)) before and after vaccination (7 day intervals until end of radiotherapy, at least on day 35 after the first vaccination). Intervals of measurement are according to the pivotal clinical trial of Walsh et al. (2020). Data on vaccination reactions/side effects were monitored. For longitudinal antibody titre evaluation the Wilcoxon rank sum test was applied (days 14, 21, 28, and 35 vs. pre-vaccination values). An alpha error of < 0.05 was considered significant. Results 74 patients could be analysed, 36% women, 64% men, median age 72 years. Distribution of tumor entities: prostate 30%, breast 16%, lung 16%, brain 15%, oesophagus 4%, head & neck cancer 4%, others 15%. Irradiated regions: pelvis 34%, thorax 22%, brain 16%, breast 16%, abdomen 5%, other 3%. Pure RT: 95%, concomitant RT and chemotherapy (ChT): 5%. In 51% of the cases RT was initiated before the first dose in 42% after the first and before the second dose and in 7% vaccination started within 6 weeks after RT. 3 patients had prior SARS-CoV-2 infection. Vaccine product: Comirnaty /Biontech/Pfizer 80 %, Vaxzevria/AstraZeneca 14% and Spikevax/Moderna 7%. Median antibody titres increased from 0 U/ml prior to vaccination to 0.9 U/ml on day 14 (p=0.001), 19 U/ml on day 21 (p=0.001), 126 U/ml on day 28 (p=0.001) and 367 U/ml on day 35 (p<0.000). 6 patients did not develop antibody titres by day 35 after the first dose and another 6 patients did not receive their second dose by day 35. Vaccine reactions: none 60%, injection site pain 19%, fatigue 11%, fever 6% and local reddening 6%. Conclusion In this patient collective undergoing localized RT, antibody response after SARS-CoV-2 vaccination was observed in 92% of the cases. Median antibody titres increased above baseline as soon as 14 days after the first dose. Vaccination was well PO-1473 Effectiveness and tolerability of SARS-CoV-2 vaccination in patients undergoing radiotherapy