ESTRO 36 Abstract Book

S388 ESTRO 36 _______________________________________________________________________________________________

two groups. Then, a subgroup analysis was performed, considering LNI risk, as assessed by the Roach formula, using different cut-off levels(Fig.1, 15%,20%,25%, and 30%). The subgroup analysis confirmed no statistically significant differences between WPRT and PORT for each nodal risk group, either in terms of bDFS, DFS OS, age <70 years (p=0.077). Only OS curve showed a better prognosis for WPRT, statistically significant in 15% and 20% nodal- risk groups(Fig.2), but not confirmed by univariate analysis.

We selected PCa patients with BR or BP after radiotherapy and/or prostatectomy that fulfil certain conditions. Our inclusion criteria were patients in NCCN high-risk group, or also in intermediate risk group with unfavourable features (primary Gleason≥4 and T≥2c). We also selected patients with PSA doubling time (PSAdt) <8 months). Pearson χ2 test was performed. Results The mean age of patients was 67 years (range 45–79). Mean PSA was of 3.4 +/- 5.7 (0.01–38.8). Mean PSAdt was 13.4 +/- 24.7 months (0.7–158.9). Gleason was ≥7(4+3) in 50% of cases. Median follow-up after the test was 13 +/- 9 months. Positive results were obtained in 48.7% of the scans. 57.9% of them showed local and/or regional disease and 42.1% had distant metastases. Tailored treatment was performed in each case. Scans were positive in 13.5% of patients with PSA<1 ng/mL and in 80.5% of patients with PSA≥1 ng/mL. For this PSA level, Sensibility and Specificity for obtaining a positive 18F-Ch-PET were 86.8 and 80% respectively (p<0.001).

Fig.1 LNI risk groups

Fig.2 OS stratified by LNI risk(WPRT blue and PORT red)

Conclusion This long-term analysis failed to demonstrate a benefit for elective WPRT compared to PORT. Due to retrospective nature, small sample, long accrual and heterogeneity of WPRT and PORT group, new studies need to create performing tools for patients’ selection. PO-0738 PET with 18F-Choline for evaluation of prostate cancer patients with biochemical relapse/persistence H. Pérez Montero 1 , M.A. Cabeza 1 , A. Gómez 2 , S.G. Guardado 1 , J.F. Pérez-Regadera 1 1 Hospital Universitario 12 de octubre, Radiation Oncology, Madrid, Spain 2 Hospital Universitario 12 de octubre, Nuclear Medicine, Madrid, Spain Purpose or Objective Current guidelines suggest 18F-choline-PET/CT imaging (18F-Ch-PET) as a diagnostic test for the evaluation of patients with recurrent prostate cancer (PCa). Although it has been shown superior to conventional techniques, the role of 18F-Ch-PET has not been established in clinical practice. The objective of this study was to evaluate the use of 18F- Ch-PET to restage patients with biochemical relapse (BR) or biochemical persistence (BP), which remains as a controversial issue. Our main goal was to optimize the selection of patients who may benefit the most from this test. Material and Methods It is a prospective study (data collected between February/2014 and October/2016). From the 110 scans performed in our centre, we selected a cohort of 78.

In patients with DTPSA<3 months, the test was positive in 87.5% of cases (p=0.03). Additionally, 57.1% or them were metastatic. Moreover, 82% of PSAdt>3 cases had negative result or their recurrence were local and/or regional (p=0.039). We stratified 3 groups of patients according of PSA velocity (PSAvel) and observed positivity in 23%, 52% and 81% of cases with PSAvel of 0, 0.1 and ≥ 0.2 ng/mL/month respectively (p<0.001).