Reduction of systemic chemotherapy by primary retroperitoneal lymph node dissection in low volume metastatic seminoma.

626 Background: Still, standard treatment of low-volume metastatic semimoma is either systemic chemotherapy or radiotherapy. Both options are associated with significant acute and long-term toxicities including mortality due to secondary malignancies in long-term follow-up. We calculated the number of potentially unnecessary chemotherapy cycles per hundred patients undergoing primary RPLND or Chemotherapy. Methods: In long-term follow-up of the COTRIMS-trial, 34 (12%) patients developed outfield relapses after a median follow-up of 41 months. All relapsing patients were cured by salvage PEB-chemotherapy. The base of our calculation are 12 recurrences on 100 Pts compared to 100 patients receiving chemotherapy upfront. Short term side effects of chemotherapy are from a historic patient cohort. Results: 12 relapsing patients received 36 cycles of PEB instead of 300 cycles of chemotherapy if given as first-line treatment. Significant PEB-associated acute toxicities mostly affect haematoxicity with neutropenia in 4 and 37 patients, resp., and febrile neutropenia in 1.7 and 14 patients, resp.. Based on our previous studies (Paffenholz P et al., World J Urol 2019; 37:1907), thrombembolic venous or arterial events are expected in 1.2 and 0.8 , resp. versus 10 and 7 patients, resp.. Therapy associated mortality would be expected in 0.2 and 2 patients, resp.. No data on long-term toxicities are available. Conclusions: All patients with relapses after primary RPLND can be cured by salvage chemotherapy. The number of chemotherapy cycles can be reduced by 88% without impairing oncological efficacy if surgery is performed in an experienced reference center. Thus overall acute toxicity rate affecting patients quality of life and even treatment associated deaths can be reduced dramatically. Although the reduction of long-term toxicities associated with cytotoxic therapy cannot be anticipated today, we strongly recommend to include primary nsRPLND in the therapeutic armentarium of clinical stage IIA/B seminomas.