ESTRO 38 Abstract book

S831 ESTRO 38

Conclusion The addition of a radiographer led clinic, with bowel habit assessment and prescription of laxatives, helped reducing the rate of planning rescan from 23% to 16.4% with only a 7.1% of rescan rate due to large rectum. This consequently reduced unnecessary radiation exposure to the patients and additional workload for the department. EP-1541 Intention to treat analysis of 68Ga-PSMA/11C- choline PET/CT vs. CT for prostate cancer recurrences A. Müller 1 , S. Olthof 2 , C. Pfannenberg 2 , D. Wegener 1 , J. Marzec 1 , J. Bedke 3 , A. Stenzl 3 , C. La Fougère 4 , K. Nikolaou 2 , D. Zips 1 , J. Schwenck 4 1 Eberhard Karls University Tübingen, Department of Radiation Oncology, Tübingen, Germany ; 2 Eberhard Karls University Tübingen, Department of Diagnostic and Interventional Radiology, Tübingen, Germany ; 3 Eberhard Karls University Tübingen, Department of Urology, Tübingen, Germany ; 4 Eberhard Karls University Tübingen, Department of Nuclear Medicine and Clinical Molecular Imaging, Tübingen, Germany Purpose or Objective Biochemical recurrence (BCR) after prostate cancer (PC) surgery is very common, even after additional salvage radiotherapy (SRT). This might be explained by target miss. Improved diagnostic accuracy provided by PET could potentially circumvent this therapeutic gap. Therefore, we evaluated the impact of simultaneous 11 C-choline and 68 Ga-PSMA PET/CT compared to standard CT imaging after surgery +/- SRT with regard to curative radiotherapy (RT) options including stereotactic body radiotherapy (SBRT) The prospective register database (064 / 2013 BO1) was searched for patients receiving both 68 Ga-PSMA and 11 C- choline PET/CT within the same day. Inclusion in this analysis was restricted to patients after radical prostatectomy +/-SRT at time of BCR. 11 C-choline PET/CT was acquired with a contrast-enhanced CT and 68 Ga-PSMA was combined with a low-dose CT. TNM-stage was assessed by two blinded investigators (JS, SCO). Ten curative treatment routines were defined including SBRT for up to 5 oligometastases. Imaging-related changes of treatment and treatment intent as well as related costs depending on stage shift after imaging were analysed. Cost calculation for in-/correct treatment was performed using the German reimbursement catalogue (“Einheitlicher Bewertungsmaßstab”; EBM) and the German medicines compendium (“Rote Liste”). Results Eighty-three patients were eligible (median PSA-level 1.9 ng/ml). Both PET-examinations led to concordant results in 72.3% of patients, while concordance of TNM-staging between 68 Ga-PSMA-PET and diagnostic CT was only 36.1%. Incorrect staging would lead to “wrong” treatment and therefore to additional treatment costs. A 68 Ga-PSMA-PET would be cost-effective if additional costs do not exceed 3,843 € (vs. CT). According to the “number needed to treat” we calculated the “number needed to image (NNI)” to avoid one “wrong” treatment for a patient. The NNI 11C- choline equals 4 and the NNI contrast enhanced CT equals 2 compared to 68 Ga-PSMA-PET to avoid one incorrect treatment. 68 Ga- PSMA-PET-staging enabled new curative options in half of the patients with previous SRT who otherwise always receive palliative ADT. Conclusion In this prospective analysis we compared the impact of three simultaneously performed imaging modalities on treatment of PC recurrences after surgery. Main findings include cost-efficacy of 68Ga-PSMA-PET by calculating the additional costs of “wrong” intended treatment occurring in approximately 2/3 of patients after conventional staging. In addition, we were able to demonstrate that 68Ga-PSMA-PET gave a high chance of curative treatment for oligometastases. Material and Methods

According to D’Amico risk classification for trial and inclusion criteria all of them were high risk. All patients completed the treatment as programmed with good tolerance. No toxicity greater than grade 2 was observed. EPIC urinary values were 81.26 and 80.49 at 6 and 12 months respectively. EPIC hormonal was 63.83 and 64.09 at 6 and 12 months respectively . EPIC bowel values for these points in time were 93.30 and 92.50. Non PSA relapse was seeing during this short follow-up. Acute GI grade 2 toxicities were 9.2% for a week after treatment. At the 1 st month GI Grade 2 toxicity showed the same percentage. At the 3 rd month GI Grade 2 was reduced to 4.5%. Acute GU grade 2 toxicity was 31.8 %. At the 1 st month GU Grade 2 toxicity decrease to 9.1%. One patient showed late GU Grade 2 at 6 months. Conclusion SBRT regime of 9 Gy to the prostate after normofracionated 60 Gy for high risk prostate cancer is feasible and well tolerated in selected patients. Decline in QoL values are seen EPIC hormonal QLQ measures are related to prolonged hormonal treatment in high-risk patients. Long-term follow-up is needed for assessment of late toxicity and outcomes. EP-1540 A bowel pathway for patients undergoing radiotherapy for prostate cancer C. Perna 1 , C. Williamson 1 , S. Khaksar 1 1 Royal Surrey County Hospital, St Lukes cancer centre, Guildford, United Kingdom Purpose or Objective To investigate whether the introduction of a new bowel pathway, in patients undergoing radiotherapy to prostate (PRT), whole pelvis (WPRT) and prostate bed (PBRT), could improve the rate of repeated planning CT scans caused by faecal loading and rectal gas. Material and Methods Data were collected retrospectively from patient’s notes and electronic records. From January 2015 until January 2016, 23% of patients underwent rescan due to faecal loading and rectal gas. Patients underwent PBRT, traditionally did not receive bowel preparation, on the contrary, those underwent PRT and WPRT used micro enemas prescribed at the time of the fiducial markers insertion. We introduced a new radiographer led clinic for all patients to discuss bowel habit and identify patients that needed additional laxatives. Patients underwent PBRT also received micro enemas routinely. All patients received a bowel chart to record their bowel movement and type of stools. Sodium Docusate 100mg TDS was our laxative of choice. In addition, a record of off-line review was kept. Results A total of 195 patients were treated (18 PBRT and 177 between PRT and WPRT) from January 2017 until April 2017. They all received, a bowel chart and the prescription of micro enemas. 32 patients also received additional prescription of Sodium Docusate. Sodium Docusate was well tolerated in all cases and therefore continued during the whole treatment helping in reducing faecal loading and rectal gas. 32 (16.4%) required a re-scan, because poor hydration, micro enema compliance and patient position. However, only 14 (7.1%) had large rectum with antero-posterior diameter >4 cm. Of the 18 PBRT patients, 15 were assessed in the radiographer led clinic and did not require a second planning scan. The 3 patients who missed the clinic underwent re-scan. The off-line review didn’t show significant differences during the course of the treatment, but data are still too small.