Post-chemotherapy retroperitoneal lymph node dissection for patients with residual masses in metastatic pure seminoma

BACKGROUND: Post-chemotherapy retroperitoneal lymph node dissection (pcRPLND) for metastatic testicular pure seminoma may be associated with significant morbidity and should be reserved for highly select cases. We report contemporary outcomes of pcRPLND in patients with metastatic pure seminoma with the goal of better defining patient selection for surgery and exploring gaps in current post-chemotherapy diagnostics. METHODS: Patients who underwent pcRPLND following ≥1-line of chemotherapy for metastatic pure seminoma at our institution between 2000-2024 were included. Clinicopathologic, radiographic, perioperative, and oncologic outcomes are reported stratified by chemotherapy received and indication for surgery (consolidative vs for suspected relapse). RESULTS: Fifty-two patients underwent pcRPLND following ≥1-line of chemotherapy, 49 in the consolidation setting and three for suspected retroperitoneal-only relapse. Residual viable seminoma was found at pcRPLND in 100% (3/3) among patients treated for suspected relapse, 23% (3/13) following first-line chemotherapy, and 6% (2/36) following ≥2-lines of chemotherapy. None of the 15 patients that received high-dose chemotherapy (TI-CE) had viable disease at pcRPLND. Over a median follow up of 50 months, five patients relapsed, all of whom had viable residual seminoma at surgery. Of patients with residual seminoma at pcRPLND, 25% were cured with surgery alone, and 38% died from progressive disease. CONCLUSIONS: The risk of finding viable residual seminoma at pcRPLND varied based on surgical indication (relapse vs consolidation) and prior chemotherapy received; the benefits offered by surgery, particularly following first-line therapy, may be limited. These data underscore the importance of careful patient selection for pcRPLND and the need for better diagnostics to guide post-chemotherapy management decisions.