ESTRO 2023 - Abstract Book

S1191

Digital Posters

ESTRO 2023

fractions). The irradiation technique that was used was a rotational RCMI (Rapidarc® ) guided by sight after the implantation of 3 intra-prostatic golden grains. Genito-urinary and gastro-intestinal toxicities were analyzed during treatment, after 4 to 6 months and after 5 years of follow-up according to CTCAEv5. We also looked for predictive factors of toxicity and survival. Results A total of 166 patients were included. Their characteristics were : Medium age = 71.4 ans [52.9—85.6] / Medium initial PSA rate = 9 ng/mL [2.6—111] / Stade T1, T2, T3, T4 respectively 34.3 %, 26.5 %, 38.5 % and 0.6 % / Gleason Score 6, 7 (3 + 4), 7 (4 + 3) and ≥ 8 respectively 22.9 %, 43.4 %, 23.5 % and 10.2 %. We excluded patients with lymph node involvement and patients with metastasis. Grade ≥ 2 genito-urinary toxicities that occurred during treatment, after 4-6 months and after 5 years of follow-up were respectively of 36.7%, 8.8% and 4.7% and grade ≥ 2 gastro-intestinal toxicities of 15.1%, 1.9% et 9.3%. We reported one grade 3 genito-urinary toxicity, two grade 4 genito-urinary-toxicities, twelve grade 3 gastro-intestinal toxicities and no grade 4 gastro-intestinal toxicity. No link was found between the occurrence of these toxicities and the other parameters that we analyzed. Only 15 patients had a progression of their cancer. After 5 years of follow-up, the progression-free survival was of 85.7%, the specific survival was of 93.3% and the global survival was of 82.4%. We only found the PSA rate and the cardiovascular risk factors to be significatively associated to the global survival in the multivariate analysis. Conclusion Mild hypofractionated prostatic radiotherapy with dose escalation is well tolerated and adds no toxicity compared to a normo-fractionated plan. Moreover, it considerably helps reducing the total duration of the treatment. These encouraging results must be confirmed with a phase III randomized trial. 1 Gachon University Gil Hospital, Gachon University College of Medicine, Department of Radiation Oncology, Incheon, Korea Republic of; 2 Samsung Medical Center, Sungkyunkwan University School of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of Purpose or Objective Small cell carcinoma of the bladder is very rare, accounting for less than 5% of all bladder cancer. It has a poor prognosis driven from its aggressive clinical feature. Due to its rarity, there is no established standard treatment yet. Materials and Methods We retrospectively reviewed patients treated with non-metastatic small cell carcinoma of the bladder at 2 tertiary hospitals between 2005 and 2021. We evaluated patient characteristics, treatment performed, and subsequent clinical outcomes. Results A total of 24 patients were included. The median age was 65 years (range, 40-91 years), and 7 patients (29.2%) had pure histology of small cell carcinoma while others had mixed pathology (small cell predominant). The median overall survival (OS) of all patients was 71.6 months (95% CI, 21.6-121.6 months), each of which was 71.6 months (95% CI, 21.2-122.0 months) for node-negative and 26.3 months (95% CI, 11.5-41.1 months) for node-positive patients. Among 17 patients with N0 disease, 11 received radical cystectomy (RC) (neoadjuvant chemotherapy (NAC): 2; RC only: 7; adjuvant chemotherapy: 2) and 6 received NAC followed by chemoradiotherapy (CRT). Patients who underwent RC did not achieve median OS, and those who underwent CRT had a median OS of 71.6 months (P=0.884). Among 7 patients with node-positive, 4 received RC (NAC:1; RC only:1; adjuvant chemotherapy: 2), 2 received chemotherapy only, and 1 received CRT, with the median OS of 19.4, 26.3 and not-reached, respectively. Upfront chemotherapy was performed in 12 patients (50%) using etoposide/cisplatin in 7 and gemcitabine/cisplatin in 5 patients, and patients who underwent upfront chemotherapy showed longer OS than in those who did not (median OS: 71.6 vs. 43.6 months; P=0.561). Among 15 patients who received RC, 7 patients with neo- or adjuvant chemotherapy showed longer OS than those who did not receive any chemotherapy (median OS: 43.6 months vs. not-reached; P=0.437). Sixteen patients (66.7%) experienced treatment failures, most of them was distant metastasis in 10 followed by pelvic nodal recurrence in 1, and local failures in 5 patients. Conclusion Patients with non-metastatic small cell carcinoma of bladder had excellent long-term survival. Node-negative patients showed better survival than node-positive patients. RC with neo-/adjuvant chemotherapy or CRT may be considered in bladder-confined disease. Large well-designed study is warranted to find the optimal treatment. PO-1470 Treatment outcomes of non-metastatic small cell carcinoma of the urinary bladder H.J. Kim 1 , K. Sung 1 , W. Park 2

PO-1471 PSMA-PET-based Definitive Radiotherapy for Patients with Prostate Cancer – Outcome and Feasibility

M.M. Vogel 1 , E.K. Sage 1 , K.A. Eitz 1 , J.E. Gschwend 2 , M. Eiber 3 , S.E. Combs 1 , K. Schiller 1

1 University Hospital Klinikum rechts der Isar, Technical University of Munich (TUM), Department of Radiation Oncology, Munich, Germany; 2 University Hospital Klinikum rechts der Isar, Technical University of Munich (TUM), Department of