Editorial by Bendu K. Konneh, John T. Lafin and Aditya Bagrodia on pp. 341-342 of this issue: MicroRNA-371a-3p as a blood-based biomarker in testis cancer.

MicroRNAs (miRNAs) are small noncoding RNAs involved in the regulation of mRNA transcription and translation, and possess all desirable features of an ideal tumor marker. Of almost 31 different miRNA clusters identified in germ cell tumors (GCTs), miR-371a-3p has shown exceptionally high sensitivity and specificity for both seminomatous and nonseminomatous GCTs. It is easily obtainable and correlates well with tumor burden. Recent multi-institutional prospective studies have shown promising test characteristics for miR-371a-3p as a diagnostic blood-based biomarker for GCT prior to orchiectomy including 80%-100% sensitivity and 90%-100% specificity. This accuracy may address other unmet needs in the management of patients with GCT. Early studies have suggested the utility of miR-371a-3p in detecting occult nodal metastasis in high-risk clinical stage I and early stage II disease. Ongoing clinical trials including SWOG 1823 and AGCT1531 are specifically designed to confirm the utility of miR-371a-3p in clinical stage I GCT. Despite its strong association with viable GCT after treatment with chemotherapy, miR-371a-3p does not seem to accurately predict the presence of teratoma in residual lesions. Also, standardization of extraction and interpretation methods is a necessary step to assure uniform results across different institutions.