ESTRO 2021 Abstract Book

S1130

ESTRO 2021

Purpose or Objective The aim of this study was to analyse the prognostic impact on clinical outcomes of prostate cancer patients treated with postoperative radiotherapy, based on a comprehensive analysis of tumor, patients, and treatment characteristics. Furthermore, we aimed at developing a simple risk stratification system based on real life data from a large patients population. Materials and Methods A retrospective analysis of 381 patients enrolled in an observational study was performed. Endpoints of the study were biochemical relapse-free survival (bRFS), local control (LC), regional control (RC), metastasis-free survival (MFS), disease-free survival (DFS), and overall survival (OS). Variables with P value less than 0.05 or with a trend (p < 0.1) at univariate analysis (log-rank) were entered into a multivariate Cox’s regression Multivariate analysis showed a lower risk of biochemical recurrence in patients with: > 61 years, pN 0 pathological stage, and lower levels of postoperative PSA. In terms of Gleason score, only patients with a value of 7 (4 + 3) showed a lower risk. In terms of LC, a higher risk was recorded in patients with lymph node metastases, similar to what was observed for RC. In addition, a higher risk of regional relapses was observed in patients with preoperative PSA levels higher than 10 ng/ml. We designed a predictive model of biochemical outcome using two age categories, two nodal stage categories, and four PSA categories to define 16 different groups of patients. These 16 groups were arranged in only three categories based on 5-year bRFS values: group 1: low-risk (bRFS > 95%), group 2: intermediate risk (bRFS: 76-95%), group 3: high risk (bRFS: < 76%). model. Results

[ Figure 1 ] Conclusion

This systematic analysis of a large patients’ series allowed identifying unforeseen correlations that can generate new hypotheses. These results justify further analysis of large series of prostate cancer patients treated with postoperative radiotherapy, possibly performed with more advanced statistical analysis methods.

PO-1381 Toxicity outcomes of salvage versus adjuvant radiotherapy for prostate cancer using VMAT and IMRT D. Fasciolo 1 , D. Fasciolo 2 , C. Rosa 1,3 , M. Marchione 4 , M. Borgia 1 , M. Lucarelli 1 , A. Vinciguerra 1 , A. Augurio 1 , L. Caravatta 1 , D. Genovesi 1,5 1 SS. Annunziata Hospital, Department of Radiation Oncology, Chieti, Italy; 2 G. D'Annunzio University, Department of Neuroscience Imaging and Clinical Sciences, Chieti, Italy; 3 G D'Annunzio University, Department of Neuroscience, Imaging and Clinical Sciences, Chieti, Italy; 4 G. D’Annunzio University, Laboratory of Biostatistics, Department of Medical, Oral and Biotechnological Sciences, Chieti, Italy; 5 G. D'Annunzio University, Department of Neuroscience, Imaging and Clinical Sciences, Chieti, Italy Purpose or Objective The benefit of adjuvant RT in presence of adverse pathologic features (ie, positive margins, seminal vesicle invasion, extracapsular extension) without lymph node metastases is well known. Moreover, timing of postoperative treatment still remains a debated argument, in order to avoid not only overtreatments but also possible treatment-related toxicities. We have conducted a retrospective analyses of prostatic patients in adjuvant or salvage setting, with VMAT or IMRT techniques after radical prostatectomy, aiming to compare rectal and bladder toxicity in both groups. Materials and Methods