ESTRO 2020 Abstract book

S593 ESTRO 2020

1 Ospedale Sacro Cuore "Don Calabria", Radiation Oncology, Negrar, Italy ; 2 ASST Spedali Civili di Brescia - Brescia University, Radiation Oncology Department, Brescia, Italy Purpose or Objective metastatic colo-rectal cancer has a poor prognosis. Stereotactic body radiotherapy (SBRT) demonstrated to increase survival in the oligometastatic disease (OMD). Nevertheless, local control of colo-rectal metastases seems to be poor, as compared to other histologies. Our study aims to explore the natural history of oligometastatic colon-rectal cancer and to determine how SBRT can delay the progression to the polymetastatic disease (PMD). Biological predictive factors of response to SBRT were also evaluated. Material and Methods 131 lung oligometastases in 47 patients were treated with SBRT at our Institution. The median number of treated lesions was 2 (range 1-5). The initial disease stage was: I- II in 12 patients, III in 14 patients and IV in 11. Median BED 10Gy was 100 Gy (range 75-180). Time to PMD (ttPMD) was defined as the time from the SBRT to the occurrence of >5 new metastases. EGFR, KRAS, NRAS, BRAF, and microsatellite instability were evaluated as predictive factors of response. Results The median follow-up was 31 months (range 3-66 months) and the median time to the oligometastatic disease occurrence was 37 months (range 24-72 months). Median ttPMC was 25.8 months (range 10-46 months). Median Progression-free survival (PFS) was 7 months (range 4-9 months). At the last follow-up, 9 patients (19.2%) are free from disease and 38 (80.8%) progressed: 21 out of them again as oligometastatic and 17 as polymetastatic. Patients with a second oligoprogression received a second SBRT course. Median OS was 39.5 months (range 26-64 months) and the 2-year OS was 71.1%. Three-year local progression-free survival (LPFS) was 80%. At the univariate analysis BRAF wild-type correlated with better LPFS (p=0.003) and PMC correlated with worse OS (p=0.00). Conclusion Our results support the use of SBRT in lung OMD, as it can delay the transition to the PMD, leading to higher OS rates. Notably, in a significant proportion of patients, we observed an oligometastatic progression amenable of a second SBRT course. Molecular factors predictive of response were identified; future larger studies may further investigate a potential prognostic role of tumor genotyping for radiotherapy personalization. PO-1028 Consolidation therapy with Durvalumab after radical CRT in stage IIII NSCLC: a preliminar analysis P. Borghetti 1 , G. Volpi 1 , J. Imbrescia 1 , M.L. Bonù 1 , A. Guerini 1 , O. Turla 1 , M. Maddalo 1 , P. Vitali 1 , L. Triggiani 1 , A. Donofrio 1 , M. Buglione 1 , S.M. Magrini 1 1 Spedali Civili di Brescia, Istituto del Radio, Brescia, Italy Purpose or Objective The PACIFIC trial investigated Durvalumab consolidation after chemoradiation treatment (CRT) in patients with unresectable, stage III NSCLC who have not progressed after CCRT. The relevant overall survival benefit in Durvalumab arm has sensibly influenced the managment of the patients treated with a curative intent. The aim of this study consists in a preliminar evaluation in terms of toxicities and critical issues related to selection and management of eligible patients to Durvalumab as consolidation immunotherapy Material and Methods Still on going, from September 2018 all the patients with unresectable, stage III NSCLC treated at Radiation Oncology Department of Spedali Civili and University of Brescia with CRT were evaluated. Patients eligible to Durvalumab as maintenance treatment were selected for

Hospital Essen- Germany, Department of Thoracic Surgery an, ; 8 Department of Oncology- West German Cancer Center- University Hospital Essen- Germany- Division of Thoracic Oncology- University Medicine Essen – Ruhrlandklinik- University Hospital Essen- Germany, Department of Oncology- West German Cancer Center- Un, Purpose or Objective The optimal treatment for patients (pts) with locally advanced non-small-cell-lung cancer (NSCLC) TNM-stage cT4 N0/1 M0 is still under debate. The purpose of this study was to examine the long-term survival of this class of patients undergoing induction chemotherapy and concurrent radiochemotherapy prior to surgery. Material and Methods Pts with histopathologically confirmed NSCLC (TNM-stage cT4 N0/1 M0) without Pancoast-symptoms treated with neoadjuvant induction chemotherapy followed by concurrent radiochemotherapy (RT/CTx) and surgical resection between 2000 and 2015 were reviewed. According to UICC guidelines [8 th edition] T4-stage was reconfirmed by a specialist radiologist according to major T4 defining features. This analysis was approved by the local ethics committee. Patients received three cycles of induction chemotherapy prior to neoadjuvant concurrent radiochemotherapy. Mediastinal staging was performed by systematic EBUS-TBNA or mediastinoscopy. Pts received three cycles of cisplatin-based chemotherapy prior to concurrent radiochemotherapy. Mean doses of 45 Gy were given either as 1.5 Gy b.i.d or 2 Gy q.e.d. with concurrent cisplatin-vinorelbine or cisplatin-etoposide. After neoadjuvant radiochemotherapy and confirmed resectability by a tumor board review, all pts underwent subsequent, curative surgery. Primary endpoint of this retrospective study was overall survival (OS). Results Altogether 67 patients (pts) (50 men, 17 women; mean age 57 years; range 33 - 79 years) were treated with neoadjuvant RT/CTx. Mediastinal (53 cases) and great vessel infiltration (45 cases) were the most frequent cT4- defining criteria. The clinical lymph node status was cN0 in 53 and cN1 in 14 patients. 70% of pts had an initial PET/CT for staging. Median follow-up was 134 months. Overall survival rates for the entire cohort at 2-, 3-, 5- years were 83.6±4.5%, 74.6±5.3%, 65.3±5.9%, respectively. 30 pts (44.8%) achieved a pathologic complete remission (ypT0, ypN0). In multivariable analysis, the ypT category was the single most predictive factor. OS at 5- years for ypT0 (n=31) was 80.7%, for ypT1 (n=11) 62.3%; ypT2 (n=17) 58.2%; ypT3 (n=4) 50% as well as ypT4 (n=4) 0% (log-rank p=0.0001). Nine pts (13.4%) encountered grade 3 esophagitis during RT. Altogether 12 pts had surgical complications, 7 pts (10.4 %) max. grade 3, 4 pts (5.9 %) max. grade 4 and 1 pt (1.5 %) max. grade 5 (pulmonary embolism and acute cor pulmonale 2 days after intervention). Brain metastases were the major site of relapse (10.4%). Margin R0 resection status was achieved 97.0%. Locoregional control was achieved in all pts with ypT0/1. Conclusion Long-term survival at about 80% was found in pts with cT4 N0-1 NSCLC after induction chemotherapy followed by neoadjuvant radiochemotherapy and undergoing resection, in whom downstaging to ypT0 was achieved. Neoadjuvant radiochemotherapy as part of the neoadjuvant regimen increased pCR rate to 45%. These data support the merit of neoadjuvant radiochemotherapy as part of a curative, multimodality treatment strategy in this group of patients. PO-1027 Disease natural history of lung oligometastatic colo-rectal cancer patients treated with SBRT L. Nicosia 1 , F. Cuccia 1 , M. Rigo 1 , V. Figlia 1 , N. Giaj-Levra 1 , R. Mazzola 1 , F. Ricchetti 1 , D. Tomasini 2 , F. Alongi 1 This abstract has been withdrawn