ESTRO 2020 Abstract book

S616 ESTRO 2020

PO-1075 Simultaneous integrated boost concepts in radiotherapy for esophageal cancer: outcomes and toxicity J. Ristau 1,2,3 , M. Thiel 1 , S. Körber 1,2,3 , F. Sterzing 1,4 , S. Katayama 1,2,3 , K. Herfarth 1,2,3,5,6,7 , J. Debus 1,2,3,5,6,7 , M. Häfner 1,2,3 1 Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany ; 2 Heidelberg University Hospital, Heidelberg Institute of Radiation Oncology HIRO, Heidelberg, Germany ; 3 Heidelberg University Hospital, National Center for Tumor diseases NCT, Heidelberg, Germany ; 4 Strahlentherapie Süd, Radiation Oncology Unit, Kempten, Germany ; 5 German Cancer Research Center DKFZ, Clinical Cooperation Unit Radiation Oncology, Heidelberg, Germany ; 6 Heidelberg Ion-Beam Therapy Center HIT, Department of Radiation Oncology, Heidelberg, Germany ; 7 German Cancer Consortium DKTK, partner site Heidelberg, Heidelberg, Germany Purpose or Objective Radiation therapy and chemoradiation play a major role in the definitive management of esophageal cancer. Considering advances in treatment of other malignancies, survival in esophageal cancer patients is still relatively poor, mostly due to high rates of local recurrence and distant metastases. It is hypothesized that dose escalation in radiotherapy could improve outcomes. Therefore, this retrospective analysis aimed to investigate the outcomes and toxicity in patients treated with local dose escalation by means of using simultaneous integrated boost concepts. Material and Methods Between 2013 and 2018, 101 patients with adenocarcinoma, squamous cell carcinoma or adenosquamous carcinoma were analysed in this monocentric, retrospective study. All patients received definitive chemoradiation or radiation therapy alone as intensity modulated radiotherapy (IMRT). The prescribed dose was 50.4 Gy in 28 fractions to the primary tumor and the elective lymph nodes as well as a simultaneous integrated boost (SIB) with 58.8 Gy in 28 fractions to macroscopic tumor and lymph node metastases. Endpoints were overall survival (OS), progression free survival (PFS), local control rate (LCR) and toxicity. Results 60 patients (59.4%) received chemoradiation, 41 patients (40.6%) radiotherapy alone. The median follow up was 17 months (range: 0-75 months). OS, PFS and LCR were at 63.9%, 53.9% and 59.9% after 1 year and 37.6%, 34.5% and 36.1% after 3 years, respectively. 16 patients (15.8%) in total developed a local recurrence within the field of radiation. In 48 patients (47.5 %) at least one grade III (CTCAE) toxicity was documented during radiotherapy, mostly dysphagia (36 pat., 75.0%). One patient suffered from a grade IV pneumonia. Two patients died during therapy (one pneumonia with sepsis and one tumor bleeding after placing a PEG). The rate of grade III dysphagia decreased to 9.8% until 3 months after the end This retrospective analysis demonstrates that SIB concepts in definitive (chemo)radiation therapy are safe and feasible while showing acceptable outcomes. Prospective studies are needed for validation. PO-1076 Gastric adenocarcinoma: Does one size fit all? R. Prasad 1 , J. McElroy 2 , N. Sebastian 1 , D. Diaz 1 1 The Ohio State University, Radiation Oncology, Columbus, USA ; 2 The Ohio State University, Biomedical Informatics, Columbus, USA Purpose or Objective Worldwide gastric cancer incidence and mortality rates vary widely with the highest rates in Asia and Latin America. Most prospective studies have been conducted in of therapy. Conclusion

increments) and lung V5-50 (in 5Gy increments). Cut-off values for dosimetric parameters were those described by Cai Xu et al. The impact of heart and lung parameters on OS was assessed using the Kaplan-Meier plots and the log rank test for univariate analysis and the Cox regression for multivariate analysis. Statistical analysis was performed with SPSSv25. Results The study included 67 patients, 59 males, with a median age of 57 years. Most patients had clinical stage III disease (n=36). Median OS was 11 months. 33 patients were submitted to surgical resection after preoperative CRT. The MHD>27Gy was significantly associated with worse OS (5 vs. 12 months; p=0.005 ), as was V15>87% (4 vs. 11 months, p=0,002 ), V20>65% (4 vs. 11 months; p=0,002 ), V45>20% (10 vs. 18 months, p=0,02 ). No lung parameters were associated significantly with OS. In the multivariate analysis, no dosimetric value had relation with OS ( p>0.05 ). Conclusion Current knowledge about prognostic factors in EC includes, among other factors, T stage, age and R-status. The present study showed that there is an statistically significative association between MHD>27Gy, V15>87% and V20>65% and worse OS. Although this was not confirmed by Cox regression, this results suggest an advantage in minimize heart doses as much as possible. This study involved a small sample size of a single institution, so further validation is required prior to incorporating heart and lung doses as a prognostic indicator. PO-1074 Adjuvant radio-chemotherapy after extended or simple cholecystectomy in gallbladder cancer. M. González Domingo 1 , P. González Mella 1 , I. Perrot Rosenberg 2 , N. Cardozo 1 , R. Martin 3 , G. Veillon Contreras 4 , M.J. Maluk Alarcón 5 1 Instituto Oncológico, Department of Radiation Oncology, Viña del Mar, Chile ; 2 Universidad de Valparaiso, Radiation Oncology, Valparaiso, Chile ; 3 Instituto Oncológico, Department of Surgery, Viña del Mar, Chile ; 4 Hospital Carlos Van Buren, Radiation Oncology, Valparaiso, Chile ; 5 Universidad de Valparaiso, General Medicine, Valparaiso, Chile Purpose or Objective To analyze results of 25 years of a single center experience of combined treatment of adjuvant radio- chemotherapy in patients with gallbladder cancer after complete resection. Material and Methods Since June 1993 until October 2019, 104 patients with the diagnosis of gallbladder cancer who underwent extended or simple cholecystectomy and were staged as T1b-2-3 N0- 1 M0, received adjuvant radio-chemotherapy at Instituto Oncológico, Viña del Mar. Overall survival and median survival were analyzed in relation to different prognostic factors, using Kaplan-Meier techniques and compared with log-rank tests. Results With a median follow-up of 41 months, the 5 and 10-year overall survival (OS) rate for the entire cohort was 44% and 37%, respectively, and the median survival time was 42 months. In the group who underwent extended cholecystectomy, the 5 and 10-year OS was 58% and 45% versus 34% and 29% for those who underwent simple cholecystectomy (p<0.05). Conclusion These long term results in gallbladder cancer treatment confirm that extended cholecystectomy and adjuvant radio-chemotherapy can achieve a long term survival rate, and can be considered a good approach for this group of patients.