The PRIMETEST trial: Prospective phase II trial of primary retroperitoneal lymph node dissection (RPLND) in stage II A/B patients with seminoma.

Abstract

420 Background: Primary retroperitoneal lymph node dissection (RPLND) in patients (pts) with stage II A/B seminoma without adjuvant local or systemic treatment is an experimental treatment to avoid radio- or chemotherapy–related toxicity. The prospective PRIMETEST trial (NCT 2015053664) evaluates recurrence-free (RFS) and overall survival (OS) as well as surgical safety of patients with clinical stage II A/B seminoma undergoing RPLND without adjuvant treatment. Interim results had been presented at ASCO GU 2019. Methods: Primary endpoint of the study is PFS after a median follow-up of 36 months. We performed unilateral open or robotic RPLND in pts with unilateral retroperitoneal lymphnode metastases < 5 cm (stage IIA and IIB) with human chorionic gonadotropin (HCG) < 5 mU/ml. Pts were included with either stage IIA/B at initial diagnosis, at time of recurrence under active surveillance, or after adjuvant carboplatin in clinical stage I. The phase II trial was designed to exclude the upper limit of a 95% confidence interval at 30% recurrences. Results: Trial accrual was completed in a single center from May 2016 to June 2021 with 33 consecutive pts. 13 and 20 pts presented with stage IIA and IIB, respectively. 9 pts had initial stage II, 19 pts presented with recurrence during active surveillance, 5 pts had adjuvant carboplatin. At time of RPLND median HCG was 0.1 mU/ml (range 0 – 2.2 mU/ml). Open and robotic RPLND was performed in 14 (42 %) and 19 (58 %) pts, respectively. One patient had to be converted from robotic to open surgery. Median size of metastasis on histological report was 28 mm (range 11 – 69 mm) with a median OR time of 169 min (range 101 – 351 min). Median estimated blood loss was 50 ml (range 0 – 400 ml). Higher grade complications (Clavien Dindo ≥ III) occurred in 3/ 33 pts (9 %; 2 x pulmonary embolism, 1 x ureteral stricture requiring ileal ureter substitute). Of 33 pts, 2 pts withdrew their consent during follow-up. As of September 1, 2021, the median follow-up is 26 months (range 2 – 56 months). Up to now we observed 10 recurrences (31 %). RFS is 69 % with a median time from RPLND to relapse of 6 months (range 3 – 36 months). The recurrences included infield recurrences in 3/ 10 cases. 5 and 5 recurrences were observed in stage II A and B pts, respectively. Analysis of predictive factors showed vascular invasion present in 5/ 10 recurrences. Half of pts with relapse were treated with robotic RPLND and open RPLND, respectively. All pts with relapse underwent standard chemotherapy and are currently without evidence of disease. Conclusions: Open and minimally invasive surgical resection of small volume, unilateral seminoma metastasis is feasible with acceptable toxicity. Current recurrence-free survival rates suggest this approach as an option to avoid standard treatment (chemotherapy, radiotherapy) in selected patients. Clinical trial information: NCT2015053664.