ESTRO 36 Abstract Book

S724 ESTRO 36 2017 _______________________________________________________________________________________________

difference in bPFS between uIR patients and fHR patients (p = 0.462). Rates of PSA recurrence in uHR patients were significantly different from fHR, as noted above, as well as with fIR (p = 0.031) while not from uIR (p=0.070). Conclusion When taking into account clinical sub-stages and biopsy core involvement there was not a significant difference in bPFS between unfavorable IR patients and favorable HR patients where only one HR risk factor is present. The presence of a single HR risk factor may not be as detrimental to prognosis as previously thought, while multiple IR risk factors or significant core involvement may alter outlook for patients in the IR group. Due to the median follow up of this study biochemical recurrence was used as the primary endpoint which makes direct comparison to studies using prostate cancer specific mortality difficult; additional evaluation using such endpoints is warranted. EP-1365 Pure Hypofractionated Radiotherapy for the Treatment of Low- to Intermediate-Risk Prostate Cancer R. Stephens 1 , D. Gopaul 2 , D. Panjwani 2 , M. Lock 3 1 Grand River Regional Cancer Centre, Oncology, Kitchener, Canada 2 Grand River Hospital, Oncology, Kitchener, Canada 3 London Health Sciences Centre, Oncology, London, Canada Purpose or Objective Radiotherapy for prostate cancer may benefit from hypofractionation 1-13 . Conventional radiotherapy for prostate cancer involves delivering daily 1.8 -2.0 Gy fractions over 9 weeks. All of the hypofractionation studies completed to-date involve delivering fewer fractions of 2.5-3.1 Gy daily for 4 to 5 weeks (i.e., they are accelerated). The purpose of our prospective phase II clinical trial was to determine whether the use of hypofractionated radiotherapy schedules (i.e., fewer, larger fractions) without acceleration could lead to reductions in the incidence of late toxicity symptoms, while still retaining benefits in disease control. Material and Methods Prostate cancer patients at Grand River Regional Cancer Centre were screened for the study, and those that met eligibility criteria were enrolled. Written informed consent was obtained. Radiation therapy was delivered using either 3DCRT or IMRT. Patients were categorized as low risk or intermediate risk according to D'Amico criteria 14 . Low risk patients received a total dose of 50 Gy / 15 fx over 7 weeks, and intermediate risk patients received 60 Gy / 20 fx over 8 weeks. Neoadjuvant or adjuvant ADT was not used. Follow-up involved bi-annual PSA measurements and toxicity grading. Freedom from biochemical failure (FFBF) was determined using the Phoenix definition 15 . Late toxicity scoring was based upon RTOG/EORTC Late Radiation Morbidity Criteria 16 . Using Microsoft® Office Excel® 2007 (Microsoft, Redmond, WA) demographic information and outcome frequencies were analysed. Actuarial analysis for freedom from biochemical failure (FFBF), late gastrointestinal (GI) toxicity, late genitourinary (GU) toxicity, freedom from evidence of metastatic disease, and overall survival were generated using in IBM® SPSS® Statistics Version 21.0 (IBM Corporation, North Castle, NY). Results There were 216 prostate cancer patients that met eligibility criteria and were enrolled in the study. 209 patients were included in the long-term analysis after 10 years of follow-up. The median follow-up was 6.5 years. Of the 209 patients enrolled, 53 patients were categorized as low risk and 156 patients as intermediate risk. Table 1 summarizes the incidence of outcome events at the end of the 10-year follow-up period.

Actuarial analysis (Figure 1) provided 5 year rates of late GI toxicity ≥ RTOG grade 2 of 4.3% in low risk patients and 7.5% in intermediate risk patients. Late GU toxicity rates were 8.6% in the low risk group and 7.6% in the intermediate group. 5 year FFBF rates were 85.1% in low risk patients and 80.1% in intermediate risk patients. The 5 year freedom-from-evidence-of-metastatic disease rates for low and intermediate risk prostate cancer patients were 4.2% and 4.8%, respectively. Conclusion Compared to accelerated hypofractionated schedules 2-11 , hypofractionation without acceleration resulted in similar rates of late GI toxicities, late GU toxicities, and 5 year FFBF rates (see Table 1). EP-1366 Radiotherapy aimed at functional preservation in patients with small cell carcinoma of the bladder. H. Akamatsu 1 , K. Nakamura 2 , T. Ebara 3 , K. Inaba 4 , S. Itasaka 5 , K. Jingu 6 , Y. Kosaka 7 , T. Murai 8 , K. Nagata 9 , T. Soejima 10 , S. Takahashi 11 , T. Toyoda 12 , S. Toyoshima 13 , K. Nemoto 1 , T. Akimoto 14 1 Yamagata University School Faculty of Medicine, Department of Radiation Oncology, Yamagata, Japan 2 Hamamatsu University School of Medicine, Department of Radiation Oncology, Yamagata, Japan 3 Gunma Prefectural Cancer Center, Department of Radiation Oncology, Ota, Japan 4 National Cancer Center Hospital, Department of Radiation Oncology, Tokyo, Japan 5 Kurashiki Central Hospital, Department of Radiation Oncology, Kurashiki, Japan 6 Tohoku University Graduate School of Medicine, Department of Radiation Oncology, Sendai, Japan 7 Kobe City Medical Center General Hospital, Department of Radiation Oncology, Kobe, Japan 8 Nagoya City University, Department of Radiation Oncology, Nagoya, Japan 9 Ishikiriseiki Hospital, Department of Radiation Oncology, Higashi Osaka, Japan 10 Hyogo Cancer Center, Department of Radiation Oncology, Akashi, Japan 11 Kagawa University Hospital, Department of Radiation Oncology, Kita-gun, Japan 12 NTT Medical Center Tokyo, Department of Radiation Oncology, Tokyo, Japan 13 Toyama Prefectural Central Hospital, Department of Radiation Oncology, Toyama, Japan 14 National Cancer Research Hospital East, Department of Radiation Oncology, Kashiwa, Japan Purpose or Objective Small cell carcinoma of the bladder (SCCB) is extremely rare, accounting for less than 1% of malignant tumors in the urinary tract. Because of its rarity, standard therapy has not been established. We conducted the first national survey in Japan on radiotherapy aimed at functional preservation in patients with small cell carcinoma of the bladder. Material and Methods Data were obtained for treatments and outcomes in patients with a diagnosis of SCCB who received radiotherapy aimed at functional preservation in the period from 1990 to 2010. A multi-center retrospective analysis of 15 eligible cases was performed. Results The median age of the patients was 72 years (range: 44- 93 years), and the median follow-up period was 17.4 months (range: 2.7-117.8 months). The median dose was 55 Gy (range: 40.0-61.0 Gy), and a median of 2.0 Gy (range: 1.2-2.0 Gy) was given per fraction. Initial CTV (clinical treatment volume) in most cases was the whole Electronic Poster: Clinical track: Urology-non-prostate