PD19-05 DOES PERCENTAGE OF SEMINOMA AT ORCHIECTOMY IMPACT PATIENT MORBIDITY AND PATHOLOGIC OUTCOMES AT POST-CHEMOTHERAPY RETROPERITONEAL LYMPH NODE DISSECTION FOR MIXED GERM CELL TUMOR?

INTRODUCTION AND OBJECTIVE: Post-chemotherapy retroperitoneal lymph node dissections (PC-RPLND) for pure seminoma are widely considered to have an increased potential for surgical complexity and morbidity secondary to increased post-chemotherapy desmoplastic changes. This places patients at increased risk, often with pathologic findings only revealing necrosis. We sought to determine if the percentage of seminoma in the orchiectomy specimen predicts necrosis on PC-RPLND for non-seminomatous germ cell tumors (NSGCT) and the associated impact on patient morbidity. METHODS: Patients with seminoma in the orchiectomy specimen who underwent PC-RPLND for NSGCT at Indiana University from 2009-2019 were identified to assess pathologic findings, required ancillary procedures at the time of PC-RPLND, and post-operative outcomes. Patients were categorized into quartiles to assess if increasing percentage of seminoma predicted necrosis. RESULTS: Of the 109 patients identified, pathologic analysis revealed necrosis in 30/109 (27.5%), malignancy 17/109 (15.6%), and teratoma 62/109 (56.9%). As percent seminoma increased by quartile, necrosis was more prevalent (23.7%, 25%, 33.3%, 41.7%), as was the radiographic size decrease in post-chemotherapy retroperitoneal masses. For patients with greater than 90% seminoma, necrosis was found 50% of the time. The incidence of concurrent nephrectomy, need for intra-operative vascular repair, and estimated blood loss during PC-RPLND was greatest in the 4th quartile. There was no significant difference in pre-operative serum tumor markers, patient age, body mass index, pre-operative comorbidities, length of stay, or post-operative Clavien-Dindo classification outcomes. CONCLUSIONS: As percent seminoma in the orchiectomy specimen increased, the incidence of necrosis, surgical complexity, and the need for concurrent ancillary procedures increased. However, it did not seem to change the hospital course or post-operative morbidity. Unfortunately, these results show that PC-RPLND cannot be eliminated even in patients with very high orchiectomy seminoma percentages as over half of these patients had teratoma or viable malignant elements in the retroperitoneum. Source of Funding: None