ESTRO 2024 - Abstract Book

S2492

Clinical - Urology

ESTRO 2024

Material/Methods:

We conducted a retrospective study to investigate the outcomes of all de novo prostate cancer patients with pelvic node dissemination but non-metastatic disease treated with radiation therapy in our institution from January 2008 to April 2023. We analyzed the patients and treatments characteristics, oncological results and toxicity (RTOG score). We compared the outcomes of patients who received pelvic irradiation with those who also received dose escalation to positive nodes. Biochemical relapse-free survival (BRFS), MFS and OS, were calculated using the Kaplan-Meier estimator. Univariate and multivariable Cox regression studies were performed to identify the variables associated with outcomes. Mann Whitney Test was used for comparative analysis.

Results:

Our analysed cohort includes 124 males with a median age of 72 years (range:46 -84). Most patients had aggressive histologies at diagnose (International Society of Urological Pathology (ISUP) 4:25.8% and 38.7% ISUP 5) with a median PSA level of 16.75 (range:1.5-389.4).

The rate of locally advanced tumour at diagnose was 49.1% (29.8%T3a, 13.7%T3b, 5.6%T4).

Relatively to systemic treatment, 93.5% associated ADT with a median duration of 36 months (range 6-54). Only 3.2% of patients received abiraterone.

The median dose prescribed to the prostate was 71.05 Gy (range:64.4-77). Most cases received prophylactic irradiation of the pelvic lymph node areas (97.6%), being the most commonly used scheme (54%) 52.20 Gy in 29 fractions (1.8 Gy/fraction). Most patients (72.5 %) received dose escalation in the affected nodes with a median escalation dose of 60.9 Gy (range:51-65.60). Radiation therapy was delivered using IMRT in 68.5% of patients, 3D-CRT in 19.4% and a hybrid technique (IMRT-3D-CRT) in 12.1%. Mann-Whitney test showed no differences on age, Gleason, clinical stage, Charlson or PSA when comparing that subgroup to the prophylactic pelvic irradiation subgroup. No benefit in any survival analysis was observed by increasing the dose on positive lymph nodes.

With a median follow-up of 55 months (range:5-192), BRFS at 1, 2 and 5 years was 100%, 94.4% and 76.7%. Table 1.

Radiological stage T3b was the only factor associated statistically with poor BRFS in the multivariable Cox regression (p:0.012, HR:9.40; CI: 1.64-53.86).