miRNA as a Liquid Biomarker for GCTs in STMs

Incidental small testicular masses (STMs) ≤2 cm are found in approximately 1% to 4% of patients who undergo scrotal ultrasounds. While most STMs are benign, between 13% and 21% are malignant. Distinguishing between them remains a challenge, as serum tumor markers and imaging methods do not offer reliable predictive capabilities for germ cell tumors (GCTs).

Data from Julian Chavarriaga, MD, and colleagues on the utilization of microRNAs (miRNAs) as liquid biomarkers for predicting GCTs in STMs were presented at the European Association of Urology Congress 2024.

Researchers collected data from 66 patients with STMs between 2009 and 2023. Each patient had banked serum or plasma prior to orchiectomy. Preorchiectomy samples were drawn between 1 day and less than 6 months before surgery and were analyzed using various miRNA extraction methods (qRT-PCR, DdPCR) and platforms across 3 research laboratory facilities.

The study’s primary end point was the association between miRNA (miR-371a-3p) and the presence of GCTs, while miRNAs 372, 373, and 367 were also analyzed for their potential ability to improve the diagnostic performance of miRNA to predict GCTs in STMs.

A total of 40 patients had confirmed GCTs, 22 had benign histology, and 4 had been on surveillance for over 12 months and were regarded as having benign STMs.

The median age was 38.5 years, and the median tumor size was 13.5 mm. Radical orchiectomy was carried out in 74% of patients, while 12% underwent partial orchiectomy. Of the patients with confirmed GCTs, 27 (67.5%) had seminoma and 13 (32.5%) had nonseminomatous GCTs. Of the patients with benign tumors, 31% were sex cord-stromal.

The first lab used magnetic beads-based serum extraction. miR371a-3p showed a sensitivity, specificity, positive predictive value, and negative predictive value rate of 67.5%, 100%, 100%, and 62.5%, respectively. The area under the receiver operating characteristic (AUROC) was 0.774. A second research laboratory examined plasma with a qRT-PCR extraction kit. miR371a-3p showed a sensitivity and specificity rate of 96.0% and 77.9%, respectively, and the AUROC was 0.912.

miR-371a-3p can detect the presence of GCTs in STMs. Further research in this area is needed to gain more insight into the management of incidental STMs.