ESTRO 2024 - Abstract Book

S2387

Clinical - Urology

ESTRO 2024

1083

Digital Poster

Oligometastatic prostate cancer: different pattern of relapse between pelvic and para-aortic disease

Edoardo Pastorello 1 , Luca Nicosia 2 , Francesco Frassine 3 , Luca Triggiani 3 , Paola Vitali 3 , Emiliano Salah El Din Tantawy 4 , Valeria Santoro 4 , Renzo Mazzarotto 4 , Stefano Maria Magrini 3 , Filippo Alongi 1,3 1 IRCCS Sacro Cuore Don Calabria, Advanced Radiation Oncology Department, Negrar di Valpolicella, Italy. 2 IRCCS Sacro Cuore Don Calabria, Advanced Radiation Oncology, Negrar di Valpolicella, Italy. 3 Università degli studi di Brescia, Department of Radiation Oncology, Brescia, Italy. 4 AOUI, Radiation Oncology Unit, Verona, Italy

Purpose/Objective:

Lymph-nodal metastases from prostate cancer (PC) are differently treated according to their site: pelvic are considered as locoregional lymph-nodes (cN1), instead positive lymph-node above aortic bifurcation is considered as distant metastases (cM1). Aim of the study was the evaluation of differences between oligometastatic para-aortic disease and pelvic disease. We report the retrospective data of a cohort of PC patients who received stereotactic body radiation therapy (SBRT) for lymph-nodal pelvic or para-aortic metastases.

Material/Methods:

Inclusion criteria were: diagnosis of oligometastatic para-aortic or pelvic lymph-nodes from PC; primary tumor previously treated with radical intent; no extra-nodal disease. Patients with de novo metastatic disease were excluded. All lymph-nodes were treated with SBRT and diagnosed through PET (PSMA or choline). Univariate and multivariate analyses were performed on global population. The two cohorts were compared for survival analyses, and Chi-squared and Fischer exact Test were performed to evaluate the pattern of recurrence. To make a comparison between the two different groups, a propensity score matching (PSM) was applied to create comparable cohorts. Primary end point of the study was the progression-free survival (PFS) between the two cohorts. Secondary end-points were biochemical relapse-free survival (BRFS), androgen deprivation therapy-free survival (ADTFS), polymetastatic disease-free survival (PMDFS), castration resistant-free survival (CRFS), local progression-free survival (LC) and pattern of relapse. Between 2012 and 2022, 164 patients were treated in three different radiotherapy institutions on oligometastatic pelvic or para-aortic lymph-nodes from PC. A total of 240 lymph-nodes were treated. 127 patients had a pelvic disease and 37 had a para-aortic disease. Median follow up was 37 months (range 7-112). Median RT dose was 35 Gy (range 21-42) in 5 fractions (range 1-6). At univariate analysis, concurrent ADT has proven to be a positive prognostic factor for BRFS (p=0,02); a lower PSA value at time of SBRT showed better PFS (p=0,036), ADTFS (p=0,034) and PFS (p=0,01) and also the simulatenous treatment of a single lymph-node against two or more was associated with higher ADTFS (p=0,006), CRPCFS (p=0,03) and PMDFS (p=0,013). The multivariate analysis confirmed positive outcomes from treating one lymph-node in ADTFS (p=0,049), CRPCFS (p=0,019) and PMDFS (p=0,03). Also, at multivariate analysis, association of ADT showed a positive effect on BRFS (p=0,01) and PFS (p=0,03). The cumulative 5-years LC was 90,5%. No toxicity events G>2 according to CTCAE 5.0 were reported. A comparison has been made Results: