Discordance of retroperitoneal and thoracic histologic findings in patients with metastatic germ cell tumors at postchemotherapy residual tumor resection.

Introduction and objectives: Postchemotherapy residual tumor resection (PC-RTR) is an important part of the multimodal treatment for patients with metastatic germ cell tumors. Simultaneous retroperitoneal and thoracic metastases often require consecutive surgical procedures. This study analyzes the histologic findings after abdominal and thoracic surgery in order to tailor the sequence and intensity of surgery.

Patients and methods: From a total of 671 PC-RTRs from 2008 to 2021 we analyzed 50 patients with stage III non-seminomatous germ cell tumor (NSGCT) who had undergone both retroperitoneal and thoracic postchemotherapy residual tumor resection after first-line and salvage chemotherapy.

Results: All patients included had stage III NSGCT. 39 and 11 patients received first-line and salvage chemotherapy, respectively. 45 (90%) patients received retroperitoneal resection first, followed by thoracic surgery. Three patients (6%) underwent thoracic surgery before retroperitoneal surgery and two patients (4%) underwent simultaneous surgery. Overall, the histology of retroperitoneal and thoracic specimens was discordant in 23% of cases. After first-line chemotherapy, of fourteen patients with necrosis in retroperitoneal histology, four patients had vital carcinoma in lung histology. In patients with teratoma in the retroperitoneum, the thoracic findings were concordant in most cases (78%). When teratomatous elements were also present in the orchiectomy specimen, concordance was 100%. After salvage chemotherapy, the discordance rate was 55%.

Conclusion: The data presented in this study underline that retroperitoneal residual masses with necrosis cannot reliably predict histologic findings of thoracic specimens. Patients with teratoma in the retroperitoneum have a high likelihood of teratoma in the thoracic specimen.