ESTRO 2020 Abstract Book

S614 ESTRO 2020

PO-1167 Salvage therapies for PSMA PET-positive nodal recurrent prostate cancer N. Schmidt-Hegemann 1 , C. Eze 1 , P. Rogowski 1 , C. Schaefer 1 , M. Li 1 , A. Buchner 2 , W.P. Fendler 3 , P. Bartenstein 4 , U. Ganswindt 5 , C. Stief 2 , C. Belka 1 , A. Kretschmer 2 1 Department of Radiation Oncology, University Hospital- LMU Munich, München, Germany ; 2 Department of Urology, University Hospital- LMU Munich, München, Germany ; 3 Department of Nuclear Medicine, University Hospital Essen, Essen, Germany ; 4 Department of Nuclear Medicine, University Hospital- LMU Munich, München, Germany ; 5 Department of Therapeutic Radiology and Oncology, Innsbruck Medical University, Innsbruck, Austria Purpose or Objective This analysis compares salvage lymph node dissection (SLND) to salvage lymph node radiotherapy (SLNRT) of 68 Ga-PSMA PET-positive nodal recurrences after radical 67 SLNRT and 33 SLND patients with pelvic and/or paraaortic nodal recurrences after RPE were retrospectively analyzed. Biochemical recurrence-free survival (BRFS) (PSA < 0.2 ng/mL) was assessed using Kaplan-Meier survival curves and log rank. For multivariable analysis, binary logistic regression analysis was performed (p<0.05). Results Median follow-up was 17 months (6 - 53) in SLND patients and 31 (3 - 56) in SLNRT patients (p= 0.027). SLNRT patients had significantly more T3/4 stages (82% vs. 67%; p= 0.006), pathologic lymph nodes (45% vs. 27%; p= 0.001) and positive surgical margins (54% vs. 12%; p= 0.001) at time of RPE than SLND patients. PSA persistence after RPE was significantly more frequently observed in the SLNRT cohort (73% vs. 27%; p= 0.001). There was no significant difference in the distribution of PET-positive lymph nodes. Median PSA before SLND was higher than before SLNRT (3.07 ng/ml vs. 1.3 ng/ml; p= 0.393). Overall, BRFS was significantly longer in the SLNRT vs. the SLND cohort (92% vs. 30%; p= 0.001) with lower rates of distant metastases (21% vs. 52%; p= 0.002) and secondary treatments (5% vs. 39%; p= 0.011) irrespective of ongoing androgen deprivation therapy at last contact. In multivariable analysis, SLNRT was significantly associated with prolonged BRFS (regression coefficient 1.436, hazard ratio 4.204, 95% CI 1.789 - 9.878; p=0.001). Conclusion This retrospective study indicates longer BRFS in patients undergoing PSMA PET-informed SLNRT as compared to SLND for recurrent prostate cancer. PO-1168 Radiotherapy in high risk prostate cancer: Whole pelvic radiotherapy vs prostate only radiotherapy A. Hernández 1 , L. Pelari 1 , G. Caddedu 1 , I. Císcar 1 , K. Ytuza 1 , S. Sastre 1 , E. Carrasco 1 , F. López 1 , C. Vallejo 1 , S. Sancho 1 , A. Hervás 1 1 Ramón y Cajal University Hospital, Radiation Oncology, Madrid, Spain Purpose or Objective We present the experience of our Radiation Oncology Department with high-risk prostate cancer patients, seen over a period of 14 years. We analyzed preliminary clinical results of a retrospective cohort of high-risk prostate cancer patients treated with External Beam Radiation Therapy (EBRT) to determine whether WPRT or prostate- only radiotherapy (PORT) yields improved Disease- Specific-Survival (DSS), Biochemical-Failure-Free-Survival (BFFS), Distant-Failure-Free-Survival (DFFS) and Regiona- Failure-Free-Survival (RFFS). prostatectomy (RPE). Material and Methods

and late genitourinary (GU) and gastrointestinal (GI) toxicity assessment was performed using Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Any PSA level rise of≥0.2 or more above the post-radiotherapy nadir was considered biochemical progression. Assuming p values ≤0.05 as significant, Chi-squared test was applied for statistical analysis. Kaplan-Meier method and log-rank test were adopted for survival estimates. Results RESULTS: Acute GU toxicities were G1 in 44% and G2 in 4.8%, no G≥3 events occurred. For GI toxicity, we reported G1 in 32.7% and G2 in 19.7%. With a median follow-up of 25 months (10-60), late toxicity rates were G2 GI in 4.7% and G2 GU in 1.8%; we also observed G3 GU in 1.8% of cases, consisting of 2 patients surgically treated for incontinence correction. At statistical analysis, pelvic irradiation was found significantly associated with acute G2 GI adverse events (p=0031). Actuarial 2- and 3-years biochemical-free survival were respectively 88.9% and 74.2% for the entire population, while in a subgroup evaluation, no difference in terms of biochemical control was observed between adjuvant or salvage treatment (p=0.28). All patients are alive, except for one death by cerebrovascular disease, resulting in 2- and 3-years overall survival rates of both 97.9%. Conclusion CONCLUSIONS: In our series moderate hypofractionated post-operative RT with Helical Tomotherapy resulted in a low incidence of adverse events, also collecting excellent biochemical control rates. PO-1166 IMRT versus 3D-CRT in the treatment of prostate cancer: comparison of outcomes and toxicity. W. Guo 1 , Y.C. Sun 1 1 Hebei Province Cangzhou Hospital of Integrated Traditional and Western Medicine, Department of Radiation Oncology, Cangzhou, China Purpose or Objective Prostate cancer is one of the most common cancers in the world. The potential benefits of intensity modulated radiation therapy (IMRT) over three-dimensional conformal radiation therapy (3DCRT) for prostate cancer primary radiation therapy treatment have not yet been clarified. Therefore, this meta-analysis was conducted to assess whether IMRT could improve clinical outcomes in comparison with 3DCRT in patients diagnosed with Relevant studies were identified through searching related databases till December, 2018. Hazard ratio (HR) or risk ratio (RR) with its corresponding 95% confidence interval (CI) was used as pooled statistics for all analyses. Results The incidence of grade 2 or worse acute adverse gastrointestinal(GI) event was analyzed and the pooled data revealed a clear decreasing trend in the IMRT compared with 3DCRT (RR=0.62, 95% CI: 0.45-0.84, p =0.002). IMRT slightly increased the grade ≥ 2 acute genitourinary(GU) adverse event in comparison with the 3DCRT (RR=1.1, 95% CI: 1.02-1.19, p =0.015). The IMRT and the 3DCRT of patients showed no substantial differences in grade ≥ 2 late GI adverse event (RR =0.62, 95% CI: 0.36- 1.09, p =0.1). In those included studies, there was no significant difference between IMRT and 3DCRT in grade 2– 4 late GU adverse event (RR =1.08, 95% CI: 0.77-1.51, p =0.65). There was a significant difference in biochemical control favoring IMRT (RR =1.13, 95% CI: 1.05-1.22, p =0.002). IMRT showed modest increase in biochemical control in comparison with 3DCRT. Conclusion In general, based on the above results, IMRT should be considered as a better choice for the treatment of prostate cancer. More randomized controlled trials are needed to determine the subset of patients diagnosed with PCa. prostate cancer(PCa). Material and Methods