ESTRO 38 Abstract book

S825 ESTRO 38

(ROC).

Purpose or Objective This is a large report including 714 consecutive patients who received postoperative radiotherapy following radical prostatectomy in Stockholm, Sweden. The aim of the study was to determine PSA outcomes in this patient cohort in relation of PSA values before radiotherapy. Material and Methods During 2008-2016 all consecutive patients in the Stockholm area treated with postoperative radiotherapy were given 70 Gy to the prostatic bed and included in this study. After radiotherapy (RT) all patients have been monitored for biochemical failure with periodic PSA controls. Results During median follow-up of 48 months, 49% of patients had no signs of biochemical failure (BcF), 13 % experienced BcF and 38 % never reached PSA nadir and subsequently progressed after RT. Five-year biochemical free survival was 47%. Patients who started RT at PSA<0.28 ng/ml had the best 5-year bPFS of 58%. Patients who started RT at PSA values of 0.28-0.7 ng/ml had bPFS at 39%, and patients who started RT at PSA >0.7 had the worst biochemical control at 33%. Conclusion Low pre-RT PSA was an independent predictor of biochemical progression-free survival (HR=1.41, p<0.001). Median pre-RT PSA for the entire cohort was 0.28 ng/l (0.2-0.45) indicating the good standard of postoperative radiotherapy process from patient referral to start of postoperative radiotherapy in Stockholm County. EP-1526 PSMA-PET/CT validates Roach formula in 280 treatment-naïve prostate cancer patients S. Koerber 1,2,3 , G. Stach 4 , C. Kratochwil 4 , M. Haefner 1,2,3 , S. Katayama 1,2,3 , H. Rathke 4 , K. Herfarth 1,2,3,5 , T. Holland- Letz 6 , U. Haberkorn 4,7 , J. Debus 1,2,3,5,8,9 , F.L. Giesel 4,7,8 1 Heidelberg University Hospital, Radiation Oncology, Heidelberg, Germany ; 2 National Center for Tumor diseases NCT, Radiation Oncology, Heidelberg, Germany ; 3 Heidelberg Institute of Radiation Oncology HIRO, Radiation Oncology, Heidelberg, Germany ; 4 Heidelberg University Hospital, Nuclear Medicine, Heidelberg, Germany ; 5 Heidelberg Ion-Beam Therapy Center HIT, Radiation Oncology, Heidelberg, Germany ; 6 German Cancer Research Center DKFZ, Biostatistics, Heidelberg, Germany ; 7 German Cancer Research Center DKFZ, Clinical Cooperation Unit Nuclear Medicine, Heidelberg, Germany ; 8 German Cancer Consortium DKTK, partner site Heidelberg, Heidelberg, Germany ; 9 German Cancer Research Center DKFZ, Clinical Cooperation Unit Radiation Oncology, Heidelberg, Germany Purpose or Objective For radiotherapy planning, the Roach formula is a very useful tool when calculating the risk of lymph node metastases for patients with prostate cancer. However, several trials suggest a risk overestimation of this mathematical approach. Therefore, the present study aimed to evaluate the accuracy of the Roach formula using prostate-specific membrane antigen (PSMA) positron- emission tomography (PET)/computed tomography (CT). Material and Methods Between July 2011 and July 2018, PSMA-PET/CT imaging was performed for almost 2500 patients. 280 patients with treatment-naïve prostate cancer and sufficient clinical data were enrolled in this study. The risk for lymph node metastases was calculated for all patients using Roach formula and PSMA data was analyzed retrospectively regarding lymph node metastases. For statistical analysis, the binary logistic regression was applied in various combinations of prostate-specific antigen (PSA), ln(PSA), Gleason score (GS) or WHO classification, to obtain new calculation methods. Afterwards, a comparison of all formulas was performed using receiver operating curves

Results Most lymph node metastases appeared in the extern iliac vessels (28.95%). For patients with a higher GS (>7), there was a higher risk for presacral metastases or a spread outside the pelvis. For classical Roach formula and a cut- off of 20%, the area under the curve (AUC) was 0.781. In contrast, the binary logistic regression formula with ln(PSA) and GS had an AUC of 0.789. Conclusion Although the AUC of the Roach formula is minimally smaller, the Roach formula can still be used for an initial assessment of the risk of lymph node metastases for patients with newly diagnosed prostate cancer undergoing radiotherapy. EP-1527 Proton therapy for prostate ca: Comparison of toxicity between mod-hypo and conventional fraction T. Waki 1 , Y. Tominaga 2 , Y. Niwa 1 , H. Ihara 1 , D. Jin 1 , S. Sugiyama 1 , T. Kawabata 1 , K. Katsui 3 , M. Fujishima 1 , S. Kanazawa 4 1 Tsuyama chuo hospital, Radiology, Tsuyama-shi, Japan ; 2 Tsuyama chuo hospital, Radiological technology, Tsuyama-shi, Japan ; 3 Okayama university, Proton beam therapy, Okayama-shi, Japan ; 4 Okayama university, Radiology, Okayama-shi, Japan Purpose or Objective To compare the acute toxicity between moderate hypofractionated (Mod-Hypo: 70 Gy (RBE) / 28 fr) and conventional fractionated (Conv: 74-78 Gy (RBE) / 37-39 fr) proton beam therapy (PBT) in patients with prostate cancer. Material and Methods We evaluated concecutive 53 patients between April 2016 to December 2017. There were 21 Mod-Hypo and 32 Conv PBT cases. Retrospective analysis of the prospectively gathered data concerning gastrointestinal (GI), genitourinary (GU), skin and other toxicity was performed. Toxicity symptoms were scored weekly during treatment period and at 3 month after the completion of treatment by 1 radiation oncologist and 1 nurse. We compared the difference in the rate of acute adverse effect score between Mod-hypo and Conv cohorts using CTCAE.ver.4.03. Results There was no severe (grade 3-4) acute toxicity. The rate of grade 1 / 2 GI toxicity in Mod-Hypo and Conv cohorts were 4.8 / 0.0% and 9.4 / 0.0%, respectively (p=0.82). The rate of grade 1 / 2 GU toxicity in Mod-Hypo and Conv cohorts were 57.1 / 9.5% and 50.0 / 25.0%, respectively (p=0.81). The rate of grade 1 / 2 skin toxicity in Mod-Hypo and Conv cohorts were 76.2 / 9.5% and 78.1 / 12.5%, respectively (p=0.87). The rate of grade 1 / 2 other toxicity in Mod-Hypo and Conv cohorts were 9.5 / 9.5% and