ESTRO 2021 Abstract Book

S567

ESTRO 2021

N. Ota 1 , K. Yasui 1 , T. Asao 1 , M. Shioi 1 , K. Hayashi 1 , Y. Ito 1 , S. Maki 1 , T. Onoe 1 , H. Ogawa 1 , H. Harada 1 , H. Asakura 1 , S. Murayama 1 , S. Deguchi 2 , K. Mitsuya 2 , N. Hayashi 2 , T. Nishimura 1 1 Shizuoka Cancer Center, Radiation and Proton Therapy Center, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture, Japan; 2 Shizuoka Cancer Center, Neurosurgery, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture, Japan Purpose or Objective To evaluate the predictive ability of the diagnosis-specific graded prognostic assessment (DS-GPA) score for survival in patients with brain metastases treated with stereotactic irradiation. Materials and Methods Data from 358 consecutive patients with newly diagnosed brain metastases from non-small cell lung carcinoma (NSCLC), breast cancer, malignant melanoma, renal cell carcinoma (RCC), or gastrointestinal tumors were analyzed retrospectively. These patients were treated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (SRT) at our institute between January 2012 and June 2019. DS-GPA scores were calculated for each patient, and patients were stratified into groups according to their DS-GPA score. The predicted median survival for each DS-GPA group was obtained from the brainmetgpa.com website. The significance of differences in actual survival between DS-GPA groups was evaluated using log-rank tests, with P<0.05 considered significant. Wilcoxon signed-rank tests were used to test the significance of differences between actual and predicted median survival. A Bonferroni corrected P value threshold of 0.002 (P=0.05/23) was used to correct for multiple comparisons. Statistical analyses were performed using JMP version 13 (SAS Institute, Cary, NC). Results The median age of the 358 patients (135 [37.7%] females) was 67 years (range 28–90 years). Among the patients, 169 (47.2%), 142 (39.7%), 46 (12.8%), and 1 (0.3%) had 1, 2–4, 5–10, and 13 brain metastases, respectively. The brain metastases originated from NSCLC (n=249; 69.6%), breast cancer (n=22; 6.1%), malignant melanoma (n=19; 5.3%), RCC (n=12; 3.3%), or gastrointestinal (n=56; 15.6%) primary tumors. A significant difference in survival between patients with different DS-GPA scores was seen in the adenocarcinoma NSCLC and non-adenocarcinoma NSCLC subgroups. In the patients with breast cancer, malignant melanoma, RCC, and gastrointestinal tumors, no significant differences were found. Median survival in this cohort was comparable to corresponding DS-GPA cohorts, and no significant differences were found. Under the unadjusted significance threshold of 0.05, a significant difference was found between the actual and predicted median survival for the 3.5–4.0 DS-GPA strata in the adenocarcinoma NSCLC subgroup (P=0.047, Wilcoxon signed-rank test). The actual median survival of the 3.5–4.0 DS-GPA strata in the adenocarcinoma NSCLC subgroup was 10.3 months shorter than predicted (33.5 vs. 46.8 months). Conclusion The DS-GPA score seems to be a useful predictor of survival in NSCLC patients with brain metastases treated with stereotactic irradiation. PD-0738 Radiosurgery in brain metastases: single vs multifraction treatment A. Rese 1 , M. Conte 2 , F. Pastore 3 , G. Ciaglia 2 , A. Pepe 4 , D. Toledo 4 , G. Panelli 4 , F. Francomacaro 4 , V. Iorio 2 1 Emicenter - Casavatore, Radiation Oncology, napoli, Italy; 2 Emicenter - Casavatore, Radiation oncology, Napoli, Italy; 3 Emicenter - Napoli, Radiation Oncology, Napoli, Italy; 4 Emicenter - Napoli, Radiation oncology, Napoli, Italy Purpose or Objective Stereotactic radiosurgery (SRS) has revolutionized the initial management of patients with brain metastases. It delivers focused, highly conformal, ionizing radiation to a target delineated using high-resolution imaging with minimal toxicity to adjacent brain structures. The most common late-delayed radiation effect of SRS is the development of brain radionecrosis (RN), which is often associated with the presence of different degrees of neurologic deficits. MF-SRS (2-5 fx) has been used as an alternative to SF-SRS, with the aim to reduce the incidence of late radiation induced toxicity while maintaining high LC rates. The aim of this retrospective study was to evaluate the acute toxicity, local control and incidence of RN in patients who received SF-SRS or MF-SRS for brain metastases. Materials and Methods In this mono-institutional analysis, 90 consecutive patients with 1 or 2 brain metastases treated with SF or MF-SRS, were included. Endpoints of the analysis were radiation-induced brain necrosis and local control (LC), progression-free survival (PFS) in SF and MF-SRS. Results 90 patients were eligible and treated with SRS from June 2017 to June 2020 and retrospectively analysed. 63 patients had lung cancer, 18 breast cancer, 5 renal cancer and 4 other cancer. Metastases were treated with Linac based radiotherapy, using VMAT tecnique. A total of 98 lesions were treated: 82 patients had 1 metastasis, while 8 patients had 2 metastases. Patients' median age was 65 years (range 40-80). Median follow up was 20 months (range 8-36 months). Patients were divided into two groups. Group A (35 patients) received a single fraction with a dose ranged from 21 Gy to 24 Gy; Group B (55 patients) received 3 fractions with a dose ranged from 24 Gy to 27 Gy. Size limits were metastases <2cm in longest diameter, largest tumor <4 ml in volume (Group A range 0.6-1.4cm; Group B range 0.6-2cm). 6 patients (7%) experienced toxicity grade 1 on the RTOG scale, without medications. 2 patients (2%) experienced toxicity grade 2 requiring home care and medication, including steroids. Every patient undergoing to perfusion and spectroscopic MRI before SRS and then every 3 months. At first follow up (3 months) 70% of patients had CR and 30% had SD, no PD. The 1-year local control rates were 76% in the SF-SRS group and 89% in the MF-SRS group. The 1-year local PFS cumulative rate was 84%, 83% in the group A and 84% in the group B. 7 patients (20%) undergoing SF-SRS and 5 (9%) subjected to MF-SRS experienced brain RN; the 1-year incidence rate of RB was 17% and 8%, respectively. Pretreatment prognostic factors associated with improved OS were female, age <65 years, KPS>80%, absence of extracranial metastases.