Oncological outcomes of primary retroperitoneal lymph node dissection in patients with clinical stage IIB seminoma: A binational retrospective analysis.

Abstract

609 Background: Primary retroperitoneal lymph node dissection (pRPLND) is emerging as a first-line treatment option for stage IIA/B seminoma, aiming to avoid long-term toxicities of chemo- and radiotherapy for long-term survivors. However, current evidence mainly involves small-volume disease (<3cm), and data for stage IIB remain limited. This study assessed oncological outcomes and recurrence predictors in patients with stage IIB seminoma undergoing pRPLND. Methods: A retrospective binational analysis was performed at two high-volume centers in Germany and the United States. Forty patients (Cologne n=20; USC n=20) treated between 2016–2025 were included. Inclusion criteria were pure seminoma, negative serum tumor markers, and clinical stage IIB. No patients received adjuvant chemotherapy. Statistical analyses identified predictors of recurrence. Results: Median (range) age was 35 years (22–67) with a median follow-up of 27 months (1–110). Preoperative imaging showed a median lymph node size of 2.5 cm (2–4.5). Median blood loss and operative time were 100mL and 154 min, respectively. Nerve-sparing was achieved in 97.5%. The median number of resected nodes was 23 (6–49), with a median of 1 (0–17) positive node and a median size of 3.05 cm (0.9–7.7). Pathology showed pN0 in 5%, pN1 in 2.5%, pN2 in 80%, and pN3 in 12.5%. Extranodal extension was present in 52.5%. Nine patients (22.5%) recurred after a median of 10 months (3–36), including 5 in-field and 4 outfield. The median size of the initial positive node in this subgroup was 4.6 cm (2.1–7.7). On univariable analysis, size of positive lymph node was the only significant predictor of recurrence (OR 2.3, 95% CI 1.21–4.7; p=0.002). Conclusions: pRPLND provides a curative option for most stage IIB seminoma patients with favorable oncological outcomes. Larger nodal disease may be less suitable for surgical management due to the increased recurrence risk, potentially warranting adjuvant or alternative therapies. Patients presenting with clinical stage IIC disease should not undergo primary surgery. Histopathological results. Median (range) number of resected lymph nodes 22.5 (6–49) Median (range) Positive lymph nodes 1 (0–17) Median (range) size of positive lymph nodes [cm] 3.05 (0.9–7.7) Nerve sparing (n, %) 39 (97.5) pN0 (n, %) 2 (5) pN1 (n, %) 1 (2.5) pN2 (n, %) 32 (80) pN3 (n, %) 5 (12.5) Extranodal extension (n, %) 21 (52.5) Recurrence (n, %) 9 (22.5) Median (range) time to recurrence [months] 10 (3–36) Infield // Outfield (n, %) 5 (55.5) // 4 (45.5) Median (range) size of initial positive lymph node [cm] 4.6 (2.1-7.7)