MP33-14: Evaluation of miRNA-371a-3p (miR371a) assay to predict final pathohistology in patients undergoing primary nerve-sparing retroperitoneal lymphadenectomy (nsRPLND) for stage IIA/B seminomas and non-seminomas
Introduction: NS-RPLND represents a guideline recommended treatment option in marker negative low volume metastatic seminomas and nonseminomas (NSGCT). However, about 30% of clinical stage IIA patients demonstrate equivocal findings of uncertain dignity so that they mgith undergo unnecessary treatment. Elevated serum concentrations of the molecular marker miR371 have been reported to correlate with the clinical stage even in small volume metastases. It was the purpose of our pilot study to evaluate the predictive accuracy of miR371 in a cohort of patients who underwent nsRPLND for clinical stage IIA/B germ cell tumors of the testis. Methods: Between 1-9/2022, 16 patients with marker negative clinical stage IIA/B seminomas (n=10) and NSGCT (n=6) underwent primary nsRPLND with a modified template resection via an open surgical approach. Blood specimens (20ml) were drawn on the day immediately prior to surgery and processed according to the manufacturer’s protocol. miRNA is extracted and purified with the Maxwell® RSC MiRNA Plasma and Serum Kits prior to its transcription into cDNA using cDNA Solution, Reverse Transcriptase and RNase Inhibitor. Subsequently, this cDNA is amplified. Using qPCR techniques, the miRNA 371a is quantified using Roche Lightcycler 480 II. Using the Lightcycler software, the median Cp (CP = crossing points) of the triplicates is calculated and converted into a RQ value (RQ= relative abundance). Results: NsRPND was performed in all patients without significant Clavien-Dindo IIIa-V complications. Mean OR time was 131 (105-195) minutes, mean blood loss was < 150ml, transfusion rate was 0%. Mean number of dissected lymph nodes was 17 (7-32), mean diameter of positive lymph nodes was 2.1 (0.8-4.1) cm. Histology revealed metastatic seminoma or nonseminoma in 12/16 (75%). In 4 patients histology revealed non-malignant disease (n=2), teratoma, and lymphoma. miR371 was positive in all 12 (100%) pts with metastases and it was negative in 3/4 (75%) pts without metastases. One patient with small volue CS IIA seminoma was false negative. Conclusions: This is the first report to demonstrate that miR371can be used as a personalized tumor marker to predict the presence of small volume retroperitoneal lymph node metastases in CS IIA/B seminomas and in nonseminomas. Patients with positive findings should undergo active treatment whereas negative findings should result in close follow-up. Date are currently validated in a multi-institutional trial. SOURCE OF Funding: None.
