Post chemotherapy retroperitoneal lymph node dissection (PC-RPLND) for metastatic pure seminoma.

Abstract

639 Background: Surgical resection of post-chemotherapy residual masses for metastatic seminoma is discussed controversially with regard to oncological and functional outcome. Furthermore, the role of FDG-PET/CT to detect vital seminoma is still unclear. It is the aim of this study is to report the outcomes of patients with pure seminoma who underwent PC-RPLND. Methods: In this retrospective international, multi-institutional study, pure seminoma patients whounderwent PC-RPLND for marker negative, FDG-PET/CT positive residual masses > 3cm or a marker negative retroperitoneal relapse following first line chemotherapy between 2000 and 2023 were included. Patients with residual masses with stable disease, negative FDG-PET/CT findings, inadequate systemic chemotherapy, insufficient clinical data, positive markers, or with residual or relapsing masses following salvage chemotherapy were excluded. Perioperative and long-term outcomes of the patients were reviewed. Results: A total of 142 patients with a median (IQR) age of 39 (31 – 68) years were included. All patients received first-line cisplatin-based chemotherapy. 93% of PC-RPLNDs were performed via an open transperitoneal approach, and 7% underwent robotic surgery. 86 (61%) and 56 (39%) patients underwent a unilateral and a full bilateral resection, respectively. A nerve sparing procedure was performed in 29 (20%). Adjunctive surgery was performed in 53 (37%) patients, the most common of which were ureteral resection/repair in 19 (13%) pts, and vascular resection/repair 18 (13%) pts followed by nephrectomy in 12 (8.4%). Median (IQR) blood loss and length of hospital stay were 550 (300 – 5800) mL and 4 (2 – 18) days, respectively. Clavien - Dindo complications ≥ 3a developed in 16 (11.3%). Final pathology revealed necrosis/fibrosis in 98 (64%) and seminoma in 44 (36%). FDG-PET/CT for residual masses > 3cm was performed in 56 patients with a positive predictive value of only 23%. On multivariate analysis (MVA) IGCCCG good risk (OR: 5.86, 95% CI 1.9-18.09, p<0.001), solitary metastases (OR 4.77, 95% CI 1.29-17.68, p=0.017) and RPLND for non-relapsing seminoma (OR 0.1, 95% CI 0.02-0,21, p< 0.001) were associated with necrosis. Adjunctive surgery (OR 4.56, 95% CI 0.39-53.5, p=0.04), and FDG-PET/CT SUV > liver (OR 31, 95% CI 2.54 – 45.6, p=0.004) and marker negative progression (OR 19, 95% CI 5.6 – 31.2, p<0.001) correlated with the presence of viable seminoma. With a median (IQR) follow-up of 65 (3 – 175) months, 20 (14%) patients relapsed (9/44 seminoma, 10/98 necrosis). 3 (3%) patients died of disease. Conclusions: One third of patients with progressive or > 3cm FDG-PET-CT positive residual retroperitoneal masses following first-line chemotherapy for metastatic seminoma may have viable tumor. 80% of patients with viable seminoma can be cured by surgery alone.In selected cases, PC-RPLND may be a valuable option if performed in high-volume centers with expertise in testicular cancer management.