ESTRO 37 Abstract book

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ESTRO 37

end of study was: 25% cancer, 3% iatrogenic events, and 32% other diseases. Bladder preservation was feasible in 79% patients; 21% had local relapse with median time 12 months. Conclusion Bladder preservation protocol results are encouraging in terms of cancer-survival and organ preservation. Furthermore, the low incidence of late recurrences becomes Combined Modality Treatment a good alternative to radical cystectomy, particularly in non- suitable for surgery patients. EP-1621 Retrospective study - Outcome of radiotherapy for invasive bladder cancer in older patients E.D. Rodrigues Pinto 1 , S. Garcia 1 , R. Lago 1 , L. Vendeira 1 , G. Pinto 1 1 Hospital de São João, Radioterapia, Porto, Portugal Purpose or Objective To assess the role of radiotherapy (RT) in bladder cancer (BC) in patients who refused cystectomy or for whom it was contraindicated. To evaluate the impact of RT in number of BC related events. Material and Methods A retrospective analysis of patients with BC treated with RT, with or without chemotherapy was carried out at our institution during the period March 2005 to March 2017, excluding patients who performed cystectomy. Events were defined as haematuria episodes requiring intravesical irrigations or transurethral resection or admission in Urology Department caused by haematuria or others symptoms related with BC. Data was statistically analyzed using IBM® SPSS® v.24. Results A total of 111 patients with BC were admitted in our institution although 53 were excluded due to pos- cystectomy status or incomplete course of RT. Fifty eight patients were included (44 men, 14 women, whose median age at diagnosis was 77 years from a range 67 - 92 years). Fifty three patients had transitional carcinoma, 1 squamous cell carcinoma, 1 adenocarcinoma, 1 sarcomatoid carcinoma, 1 lymphoepithelioma-like carcinoma and 1 neuroendocrine tumour. Eight patients received chemotherapy, 3 of them due to trimodal therapy. Nine patients were treated with RT dose below 50 Gy (20-45Gy, dose per fraction 2.5-4Gy), in relation with non-resectable disease, nodal involvement, presence of metastasis or poor performance status. Fourty nine patients were treated with RT dose above 50Gy (maximum 60.4Gy, dose per fraction 1.8/2Gy). Pathologic or clinical stage were pT1: 7 (13%), pT2: 29 (51%), pT3/cT3: 9 (17%), cT4: 11 (19%), N+: 15 (26%) and M1: 3 (5,2%). The median follow-up time was 24 months (range 4 – 176 months) and at the date of data collection 10 patients were alive without BC, 5 alive with BC, 34 died in relation with BC and 9 died from other causes not related with BC. In the group treated with RT dose below 50 Gy the overall survival at 1, 2 and 3 years was 67%, 40% and 20%, respectively. The BC-specific survival at 1, 2 and 3 years was 75%, 45% and 23%, correspondingly. A Wilcoxon Signed-Ranks Test indicated that number of events after RT were statistically significantly lower than number of events before RT (Z= -2.232, p= 0.026, r= -0.526).In the group treated with RT dose above 50 Gy the overall survival at 1, 2 and 3 years was 81%, 58% and 43%, respectively. The BC-specific survival at 1, 2 and 3 years

was 83%, 65% and 51%, correspondingly. A Wilcoxon Signed-Ranks Test indicated that number of events after RT were statistically significantly lower than number of events before RT (Z= -2.536, p= 0.011, r= -0.256). Conclusion This therapeutic approach can have an important role in older patients with bladder cancer, in terms of reducing disease related events. Symptom control was significantly achieved in both therapeutic groups. EP-1622 Irradiation alters PD-L1 expression in RCC cell lines via IFN-gamma independent pathways. Q. Tang 1 , S. Lie 2 , P. Guan 1 , B.T. Teh 1 , K.W. Yeoh 2 1 National Cancer Center Singapore, Medical Sciences, Singapore, Singapore 2 National Cancer Center Singapore, Radiation Oncology, Singapore, Singapore Purpose or Objective The immune checkpoint target PD-1 has reinvigorated the interest for Renal Cell Carcinoma (RCC) treatment in the field of immunotherapy. Yet, its success has been limited by suboptimal response rates due to acquired resistance employed by tumour cells via mechanisms not yet identified. Radiation therapy which is a modality used in over 50% of all cancer patients is mostly reserved for palliative settings in RCC. Interestingly, it has been shown to have immunomodulatory effects to enhance the efficacy of immunotherapy for unresponsive tumours. In this study, we aim at investigating how radiation affects PD-L1 and cytokines in RCC tumour cells after radiation. Material and Methods We employed ATP cell viability assay to determine the survival and growth rate of two RCC cell lines when subjected to irradiation. We also established radiated RCC cell lines through one-dose treatment and the surviving cells was measured and collected through clonogenic assay. To study the PD-L1 expression as the basis of our study, we employed quantitative PCR, Flow cytometry and immunoblotting. Cellular signalling pathway was measured via immunoblotting and the cytokine productions was measured using Luminex Multiplex assay as well as ELISA. Results Our study showed that radiation therapy may have immunomodulatory effects for RCC cell lines by regulating PD-L1 expression through mechanisms other than the canonical IFN-γ activation. The analysis on cytokine and gene enrichment study suggested that the PD-L1 response may be regulated through inflammatory cytokines and chemokines-related pathways

Figure 1.Expression of PD-L1 Through Flow cytometry and qPCR