ESTRO 2020 Abstract Book

S635 ESTRO 2020

Purpose or Objective To evaluate clinical outcomes and prognostic factors in patients (pts) affected by localized prostate cancer (LPC) treated with 3D Conformal high dose rate (HDR) brachytherapy (BT) as monotherapy. Material and Methods Between March 2004 and October 2017, 277 pts with (LPC) (T1c-T2cN0M0) were treated in our institute with HDR BT. The mean age was 67 years (range=47-81). Of them, 166 pts were low risk, 145 intermediate risk, and 15 high risk. Overall, 149 patients received 38 Gy in 4 fractions (2 fractions/day in 2 days), 41 patients received 27 Gy in 2 fractions (1 fraction/day), and 87 patients received 19-20 Gy in 1 fraction. The treatment plan was elaborated using CT based software to perform 3D conformal dose planning using these dosimetric constraints: Rectum D2cc <75% of prescription dose (PD); D2cc of bladder <80%PD. For the urethra: (D1%)<115%PD and D10%<110%PD. The prescription for the target was D90%>95%PD. Results Overall survival and cancer specific survival rates were 90% and 97% respectively. The median follow-up was 6 years (range=6-160 months) and biochemical-free disease (BFD) rate was 78%. Patients with low and intermediate risk disease had one advantage in terms of BFD compared to pts with high risk disease ( p =0.04, HR=2.453). Also, in pts patients with (iPSA)<9.5 ng/ml there was one advantage in terms of BFD compared to pts with iPSA≥9.5 ( p =0.022, HR=2.042, 95% CI=1.123-4.081). Moreover, pts who reached a nadir of PSA <0.2 ng/ml and had a PSA value<0.5 ng/ml 3 months after BT treatment had a benefit in terms BFD ( p =0.003 and p =0.001, respectively). In the same way, pts who reached the nadir within 12 months after BT treatment reported a statistically significant advantage in terms of biochemical recurrence ( p =0.01). Patients treated with a total dose of 38 Gy in 4 ff or 27 Gy in 2 ff showed a benefit in terms of BFD compared to pts treated with a total dose of 19-20 Gy in one fraction ( p =0.0001, HR=6.813). Finally, pts with low-intermediate risk disease had an advantage in terms of OS compared to pts with high risk ( p =0.034). There were not statistically significant differences regarding the analyzed risk factors and overall survival. Conclusion High risk disease and total prescribed doses were prognostic factors regarding bochemical recurrences. PSA nadir <0.2 ng/ml, iPSA<9.5 ng/ml, PSA<0.5 ng/ml three months after BT and NADIR reached within 12 months after BT resulted predictive factors regarding biochemical control. PO-1205 Small cell carcinoma of the bladder: Retrospective long-term outcomes of chemoradiation J. Oh 1 , B. Eigl 2 , P. Black 3 , K. Sunderland 4 , S. Tyldesley 1 1 BC Cancer, Radiation Oncology, Vancouver, Canada ; 2 BC Cancer, Medical Oncology, Vancouver, Canada ; 3 University of British Columbia, Urologic Sciences, Vancouver, Canada ; 4 BC Cancer, Population Oncology, Vancouver, Canada Purpose or Objective To describe the epidemiology, cohort characteristics, and treatment patterns of limited stage small cell urothelial bladder cancer (SCUC) patients in British Columbia (BC) province, and to compare the oncologic outcomes of surgery and concurrent chemo-radiation (CRT) for SCUC treated in BC Material and Methods Charts of all patients who have been referred to BC Cancer from 1985 – 2018 with histologic diagnosis of SCUC were reviewed. Canadian Institute of Health Information (CIHI) Poster: Clinical track: Urology-non-prostate

database was used to extract additional SCUC patients treated with upfront cystectomy. Patients with distant metastatic diseases at diagnosis and/or palliative intent therapy were excluded. Stage was converted to AJCC 8th edition staging for clinical staging for both surgical and non-surgical cohorts. Multivariate analysis (MVA) was performed to compare overall survival (OS) and cancer specific survival (CSS) between surgical vs non-surgical groups Results 79 patients were identified: 42 chemoRT, 35 in surgical. Median RT dose was 50Gy (EQD2 52 using a/b ratio of 10).On regression analysis, surgery cohort tended to be younger (OR 0.93, p = 0.04, CI 0.87 – 1.0), lower clinical stage (OR 0.14, p < 0.01, CI 0.04 – 0.56), diagnosed later years (OR 4.8, p = 0.03, CI 1.2 – 20). 5 year OS for CRT and surgery arm were 38% and 33% respectively (p = 0.69). 5 year CSS were 52% and 36% respectively (p=0.22). On MVA, higher ECOG, younger age, and lack of chemotherapy were associated with worse OS.

Conclusion Population-based retrospective chart review suggests no significant difference in CSS and OS between the surgical and chemoRT groups for curative small cell bladder cancer. Younger age, worse ECOG, and lack of chemotherapy are associated with worse OS and CSS. This is the largest series comparing surgery and CRT for localized SCUC in North America to this date. PO-1206 Immune response gene expression analysis and response to radical chemoradiation in bladder cancer M. Anjanappa 1 , D. Roberts 2 , K. Reeves 2 , Y.P. Song 1 , N. Akturk 3 , A. Choudhury 2 1 The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom ; 2 University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom ; 3 Dokuz Eylül University Medical School, Oncology, İzmir, Turkey Purpose or Objective The presence of tumour infiltrating lymphocytes (TILs) is prognostic in a number of solid tumours such as colon, lung and breast. An immune supressed tumour microenvironment is a poor prognostic factor thought to be due to a limited host response to cancer cell death. The immune response gene analysis enables characterisation of the TILs and the responsible pathways. Bladder cancer is known to be influenced by immune modulation. We hypothesised that the immune genotype of muscle- invasive bladder cancers treated with radical chemoradiotherapy would stratify for distant failure. Material and Methods Between 2012 and 2014, fifty patients with muscle invasive bladder cancer underwent radical radiotherapy (52.5Gy in 20 fractions) with concurrent gemcitabine (100mg/m 2 ) as