ESTRO 2020 Abstract book

S94 ESTRO 2020

37 studies with 3786 enrolled patients were identified. ICI- RT was associated with higher 1-year OS vs . mono-RT (Table 1). The only factor affecting treatment outcomes was the administration sequencing of ICI and RT combinations; the highest 1-year OS was observed for a concurrent regimen of the combination, followed by sequential regimens and mono-RT (67%, 51% and 30%, respectively). No differences in 1-year LC and RNR were found (Table 1). Table 1. Comparison of treatment outcomes for ICI-RT and mono-ICI

Besides, increasing age, lower KPS, less than GTR status were associated independent factors for reduced survival. Conclusion Patients with GBMs contacting the VSVZ and SGZ neurogenic zones exhibit divergent clinical patterns of tumor recurrence and survival and VSVZ involvement are associated with early recurrences and lower survival. VSVZ has a rich stem cell and growth factor microenvironment and these structures can be considered as organs at risk in uninvolved disease for probably better outcomes. PD-0174 Predictive factors for local and distant brain control and survival after SRT of brain metastases K. Holub 1,23 , G. Louvel 2 1 Universitat de Barcelona- Hospital Clinic de Barcelona, Radiation Oncology, Barcelona, Spain ; 2 Gustave Roussy, Radiation Oncology, Villejuif- Paris, France ; 3 SEOR-CRIS Fundation Purpose or Objective Brain metastases (BMs) are the most common adult intracranial tumors with the growing prevalence. Stereotactic radiotherapy (SRT) has greatly improved their local control (LC), but scores to predict distant control (DC) and overall survival (OS) after SRT are lacking. This study aims to investigate the factors related with local and distant brain progression free survival (LPFS, DPFS), OS and survival limited by neurological death in patients with BMs treated with upfront or post-surgical SRT. Material and Methods The data of 652 consecutive adult patients with 1565 newly diagnosed BMs from histologically confirmed solid tumors, treated with SRT between January 2012 and December 2018 in a large European cancer centre were retrospectively reviewed. In order to evaluate the predictive factors for LPFS, DPFS and OS, the following variables were evaluated: primary tumor histology, time to BMs diagnosis (> 6 months), BM location, gross tumor volume (GTV), planning target volume (PTV), single BM (vs. multiple), total dose of SRT ≤ 20Gy, whole brain radiotherapy (WBRT) prior to SRT, number of SRT fractions. Survival outcomes of patients with upfront and postoperative SRT were analysed separately. All statistical tests were two-sided (p<0.05), Kaplan-Meier’s and Cox regression models were used applied (SPSS v.23). Results SRT was administrated to 567 patients as an upfront treatment of 1399 BMs and to 156 patients with 166 postoperative cavities; 83 patients received both post- surgical and upfront SRT to different lesions. Median age at SRT was 60.3years. Most frequent histologies were NSCLC (267p, 40.9%), melanoma (130p, 19.9%), breast (70p, 10.7%), renal (48p, 7.4%), and colorectal cancer (21p, 3.2%). In patients treated with upfront SRT, lower LPFS was associated with melanoma and GTV>1.5cm3, while breast cancer determined better LC. In terms of DPFS, NSCLC histology was prognosticator of worse LC, while single BM, melanoma and renal cancer histology, and WBRT prior to SRS determined better DC. Superior mOS was observed in patients with single BM, control of extracraneal disease at the time of SRT and time to BMs diagnosis>6m. In patients with postoperative SRT, LC was better in small lesions (PTV<30.0cm3, p=0.033), while DPFS was nearly 5 times longer in single BM compared with multiple BMs (36.7m vs. 7.7m, p=0.000). In a cohort of patients whose death was determined by brain progression, single BMs (p=0.012) and smaller lesions (PTV < 30.0cm 3 , p=0.000) were associated with better mOS. Infratentorial BM location was associated with worse mOS (9.7 months vs. 18.9 months in supratentorial BMs, p=0.008). Conclusion Our results on the impact of primary tumor histology, number, size and location of BMs, and characteristics of

Incidence rate, % (95% CI): m ono-RT

Incidence rate, % (95% CI): ICI-RT Concurrent: 69 (60-78) Sequential: 52 (45-58) Unknown: 59 (52-66)

Risk ratio (95% CI)

p- value

p- value

1- year OS

1.67 (1.40- 1.98)

<.0001

32 (25-40)

<.0001

1- year LC

1.04 (0.88- 1.22) 1.60 (1.00- 2.56)

68 (46-86) 80 (73-87)

0.73

0.67

9.0 (5.0-14) 0.37

0.05

RNR 6 (2-13)

Conclusion ICI-RT combinations demonstrated higher efficacy and a comparable safety profile vs . mono-RT; superiority of concurrent combination regimens was shown. PD-0173 Ventricular – Subventricular zone involvement – A Predictive factor for survival in Glioblastoma V. Pareek 1 , R. Bhalavat 2 , M. Chandra 2 , N. Reddy 2 , Z. Moosa 2 , A. Rungta 2 , D. Kawale 2 , S. Patel 2 , L. Nellore 2 , K. George 2 , D. Borade 2 , K. Kalariya 2 , P. Bauskar 2 , N. Kumar 2 1 National Cancer Institute- AIIMS, Radiation Oncology, New Delhi, India ; 2 Jupiter Lifelines Hospital, Radiation Oncology, Thane, India Purpose or Objective MRI imaging is an essential tool in diagnosing glioblastoma and it can give various anatomical details related to disease. It gives an assessment of involvement of disease with ventricular – subventricular zone (VSVZ), subgranular (SGZ) and corpus callosum (CC). This study aims at assessment of survival outcomes in diseases involving neurogenic zones and corpus callosum and the associated prognostic factors. Material and Methods We retrospectively analyzed 376 adult patients treated for histologically proven Glioblastoma. MRI studies were assessed for the tumor volume and its association with the neurogenic zones and corpus callosum. Age of patient, comorbidities associated, performance status, extent of resection and radiation doses received by these structures were evaluated. Overall (OS) and progression free (PFS) survivals were calculated and analyzed with multivariate Cox analyses. Results Of the 376 patients, 121 had VSVZ involved, 62 had CC involved and 43 had SGZ involved and remaining 150 had cortical involvement and the latter served as controls. Overall median age was 60.4 years, median Karnofsky performance score (KPS) was 80 and median tumor volume was 34.7 cm 3 . Gross total resection (GTR) was seen in 50.6% and subtotal resection in 38.1% and rest were unresectable. On multivariate cox analyses, VSVZ was found to be an independent factor for poor OS and PFS.