Clinical outcome of robot-assisted residual mass resection in metastatic nonseminomatous germ cell tumor

PURPOSE: To evaluate the outcome of robot-assisted residual mass resection (RA-RMR) in nonseminomatous germ cell tumor (NSGCT) patients with residual tumor following chemotherapy. PATIENTS AND METHODS: Retrospective medical chart analysis of all patients with NSGCT undergoing RA-RMR at two tertiary referral centers between January 2007 and April 2019. Patients were considered for RA-RMR in case of a residual tumor between 10 and 50 mm at cross-sectional computed tomography (CT) imaging located ventrally or laterally from the aorta or vena cava, with normalized tumor markers following completion of chemotherapy, and no history of retroperitoneal surgery. RESULTS: A total of 45 patients were included in the analysis. The Royal Marsden stage before chemotherapy was IIA in 13 (28.9%), IIB in 16 (35.6%), IIC in 3 (6.7%) and IV in 13 patients (28.9%). The median residual tumor size was 1.9 cm (interquartile range [IQR] 1.4–2.8; range 1.0–5.0). Five procedures (11.1%) were converted to an open procedure due to a vascular injury (n = 2), technical difficulty (n = 2) or tumor debris leakage (n = 1). A postoperative adverse event occurred in two patients (4.4%). Histopathology showed teratoma, necrosis and viable cancer in 29 (64.4%), 14 (31.1%), and two patients (4.4%), respectively. After a median follow-up of 41 months (IQR 22–70), one patient (2.2%) relapsed in the retroperitoneum. The one- and 2-year recurrence-free survival rate was 98%. CONCLUSION: RA-RMR is an appropriate treatment option in selected patients, potentially providing excellent cure rates with minimal morbidity. Long-term outcome data are needed to further support this strategy and determine inclusion and exclusion criteria. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00345-020-03437-z) contains supplementary material, which is available to authorized users.