SEMS trial: Result of a prospective, multi-institutional phase II clinical trial of surgery in early metastatic seminoma.

Abstract

375 Background: Chemotherapy or radiotherapy are standard treatments for stage II seminoma, though they are associated with significant long-term treatment-related toxicities. Retroperitoneal lymph node dissection (RPLND) is an established treatment for testicular germ cell tumors but little data exists on its efficacy as a front-line treatment in early metastatic (stage II) seminoma. This is a single-arm, multi-institutional (NCT02537548), phase II study of retroperitoneal lymph node dissection (RLND) as first-line treatment for testicular seminoma with isolated retroperitoneal disease. Methods: Twelve sites in the United States and Canada prospectively enrolled patients (16 years of age) with testicular seminoma and isolated retroperitoneal lymphadenopathy between 1-3 cm in size. Patients were excluded if they received prior therapy (except orchiectomy) for testicular cancer. Open, modified-template RPLND was performed by qualified surgeons with a primary endpoint of 2-year recurrence-free survival. Data on complication rates (short and long-term), pathologic up/downstaging, recurrence patterns, adjuvant therapies, and treatment-free survival were assessed. Results: A total of 55 patients were enrolled and underwent RPLND. Fourteen patients had initial stage I disease who developed isolated retroperitoneal relapse while 41 patients had clinical stage IIA-B at presentation. With a median follow-up of 24 months (8-52 months), there were a total of 10 recurrences. The overall recurrence rate was 18% with a median time to recurrence of 8 months. Of the recurrences, 8 underwent chemotherapy (6 BEP X 3, 1 EP X 4, 1 carbo/etoposide) and 2 underwent additional surgery. The two-year recurrence free survival was 87% and the overall survival was 100%. There were 7 (13%) patients who experienced short-term complications within 1 year of RPLND. Of these, 5 (9%) were classified as Clavien Dindo I-II and 2 (3.6%) were classified as Clavien Dindo III. No patients have reported long-term complications. Conclusions: This trial establishes RPLND as a therapeutic option as a first-line treatment in early metastatic seminoma. The surgery offers cancer control rates similar to those seen in non-seminomatous germ cell tumors. Clinical trial information: NCT02537548.