ESTRO 2020 Abstract Book

S554 ESTRO 2020

Results Patients with disease progression displayed distinct distribution patterns of peri-treatment PBC compared to patients without. Greater prediction capabilities for risk of locoregional disease progression were found in PBC collected after the start of radiotherapy compared to their pretreatment counterparts, and in individual parameters rather than cell-to-cell ratios. The most predictive PBC parameters were integrated by summation and designated as a PBC score (PBCS), which further augmented their predictive power. Patients divided according to their PBCS (high vs medium vs low) had significantly different 3-year cumulative hazards of locoregional progression (58% vs 29% vs 7%, P = 0.0017). Multivariate analysis confirmed that PBCS high (HR 12.2, 95%CI 2.0-76.3, P = 0.007) and medium (HR 5.8, 95%CI 1.2-27.7, P = 0.028) are independent indicators of locoregional progression. Conclusion In this study, we show that peri-treatment PBCS can predict the long-term hazard of locoregional progression after definitive chemoradiotherapy in patients with esophageal squamouos cells carcinoma. Our results suggest that investigations of PBC need to be expanded from pretreatment assessments to a more systematic approach with longitudinal and multiple assessments during therapy, to generate their potential predictive value. Additionally, an appropriate integration of multiple PBC as a score could provide greater prediction power than the commonly used cell-to-cell ratios, supporting its application in further clinical studies. PO-1041 Gender disparity in esophageal cancer -- a nationwide propensity score-matched study Y. Chou 1 , Y. Lee 1 , H. Tseng 1 , J. Chiou 2 , J. Huang 3 1 Chung Shan Medical University Hospital, Radiation Oncology, Taichung, Taiwan ; 2 Chung Shan Medical University, School of Health Policy and Management, Taichung City, Taiwan ; 3 Chung Shan Medical University Hospital, Department of Medical Research, Taichung, Taiwan Purpose or Objective Gender disparity in esophageal cancer in Asian population remains unclear. Here we reported the sex differences in the outcome of esophageal cancer treatment using a national cancer registry database. Material and Methods Between 2010 and 2015, patients newly diagnosed with esophageal cancer were identified in the Taiwan Cancer Registry database. Balance between sexes was reached by propensity score-matched (PSM) analysis. The overall survival (OS) rates and its differences between sexes were calculated using the Kaplan-Meier method and log-rank test. The prognostic factors were identified by using the Cox regression hazards model. Results After PSM, 796 pairs of men and women were included in the study. Sex, age, clinical stage, treatments (surgery, radiotherapy, chemotherapy), body mass index (BMI), smoking status are prognostic factors for OS after PSM. Women had a better OS than men (p<0.0001). In subgroup analyses, men with a pretreatment BMI value >24 Kg/m 2 have a similar prognosis than women (p=0.5280), while others don’t (p=0.0066 for BMI < 18.5 Kg/m 2 and p<0.0001 for BMI 18.5-24 Kg/m 2 ).

Conclusion Women diagnosed as having esophageal cancer have better survival outcomes than men do, especially in those with lower BMIs. There's no significant sex differences in OS in patients who had a pretreatment BMI greater than 24 Kg/m 2 PO-1042 SBRT vs conventionally fractionated radio- chemotherapy for pancreatic cancer: a case-control study A. Arcelli 1 , F. Bertini 1 , A.G. Morganti 1 , A. Guido 1 , F. Deodato 2 , S. Cilla 3 , V. Scotti 4 , M.E. Rosetto 5 , I. Djan 6 , S. Parisi 7 , S. Cammelli 1 , G.C. Mattiucci 8 , M. Fiore 9 , P. Bonomo 10 , A. Bacigalupo 11 , R.M. Niespolo 12 , P. Gabriele 13 , N. Simoni 14 , R. Mazzarotto 14 , G. Macchia 2 1 Radiation Oncology Center- University of Bologna, Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy ; 2 Radiotherapy Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy ; 3 Medical Physic Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy ; 4 Casa di Cura San Rossore, Casa di Cura San Rossore, Pisa, Italy ; 5 Radiotherapy Unit, Ospedale Belcolle, Viterbo, Italy ; 6 Institute of Oncology Vojvodina-Sremska Kamenica, Medical Faculty- University of Novi Sad, Novi Sad, Serbia ; 7 Radiotherapy Unit, Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo- Foggia, Italy ; 8 Policlinico Universitario "A. Gemelli", Department of Radiotherapy- Catholic University of Sacred Heart, Rome, Italy ; 9 University Campus Biomedico, Department of Radiotherapy, Rome, Italy ; 10 Azienda Ospedaliero- Universitaria Careggi, Department of Radiotherapy- University of Florence, Florence, Italy ; 11 IRCCS AOU San Martino, Department of Radiotherapy, Genova, Italy ; 12 Azienda Ospedaliera San Gerardo, Radiotherapy Unit, Monza, Italy ; 13 Fondazione del Piemonte per l'Oncologia- IRCCS Candiolo, Department of Radiotherapy, Turin, Italy ; 14 University Hospital, Radiotherapy Unit, Verona, Italy Purpose or Objective Conventionally fractionated external beam radiotherapy + chemotherapy (RCT) or chemotherapy (CHT) alone are both well-established options for locally advanced pancreatic cancer (LAPC), while Stereotactic body radiotherapy (SBRT) is an emerging option for LAPC. Aim of this multicentric case-control study is to compare two cohorts of LAPC patients treated with RCT +/- CHT or SBRT +/- CHT in terms of overall survival (OS), local control (LC), distant metastases-free survival (DMFS), disease-free survival (DFS), and toxicity. Material and Methods Eighty patients were included. Patients in the two cohorts were matched according to: age 3.9 cm; cT; cN; neoadjuvant or adjuvant CHT. Median prescribed total dose was 30.0 Gy (range: 18.0-37.5) and 54.0 Gy (18.0- 63.0) for SBRT and RCT cohort, respectively. Toxicity was