Vertebral surgery in the management of complex postchemotherapeutic retroperitoneal lymph node dissection (PC-RPLND).

610 Background: The involvement of the skeletal system is rare in patients with metastatic testicular germ cell tumors (mGCT). Only about 3-5% of patients demonstrate involvement of the vertebral spine either by solitary metastases or due to continuous infiltration by retroperitoneal lymph nodes. We report on a consecutive series of 14 patients who underwent interdisciplinary surgery to resect residual vertebral metastases at time of postchemo RPLND and to improve oncological outcome. Methods: We retrospectively reviewed our consecutive series of 495 post-chemo RPLNDs from 2017 to 2025 and we identified14 patients who underwent both postchemo RPLND and resection of solitary or oligometastases to the vertebral bodies. The surgical approach was standardized with all patients undergoing a 2-stage procedure: dorsal stabilization followed by thoracoabdominal or transperitoneal resection of the residual retroperitoneal masses with resection 1-2 vertebral bodies in the same session. Vertebral bodies were replaced by carbon composite cages. Complications were evaluated according to Clavien-Dindo classification; oncological outcome was evaluated in terms of progression-free, cancer-specific and overall survival. Results: Median age was 24.9 (18-39) years, all pts had ECOG performance status 0-1. mGCT patients presented with good, intermediate and poor prognosis in 14%, 43% and 43%, resp., and received 3 to 4 cycles PEB. Tumor marker were normalized or plateaued in 86% and 14%, resp. Median operation time for the first session was 2.5 (2-3.5) hours; median OR time for the second session was 8.7 (6-11) hours. 5 patients required adjunctive surgeries with nephrectomy and aortic replacement in 3 and 2, resp. Median blood loss was 650 (320 – 2500) ml with 3 pts requiring red blood cell transfusions. Mean length of hospital stay was 9.8 (7-32) days. Clavien-Dindo grade 3a/b developed in 3 (21%) patients; no grade 4/5 complication and no neurological deficits were observed. Histology of the resected lymph nodes revealed viable cancer, teratoma and fibrosis in 2, 12 and 0 pts, resp. The bone specimens revealed no viable disease, but teratoma or malignant somatic transformation in 9 pts. Median follow-up is 34 (6-55) months. Overall and cancer specific survival is 100% and progression-free survival is 86%. Conclusions: The approach of en bloc surgical resection of residual retroperitoneal and vertebral metastases from mGCT is feasible and it associated with good oncological outcome associated with low surgery associated morbidity. Evaluation of complete surgical resectability, advanced experiences in skeletal and retroperitoneal surgery are essential preconditions for acceptable oncological and functional outcome.