LAUSR

BACKGROUND Circulating microRNAs have clear potential for improving malignant germ-cell-tumor (MGCT) diagnosis. Here, we address the central issue of whether measurement of a single microRNA is sufficient for detecting testicular MGCTs, or whether there is added benefit in quantifying other members of the 4-microRNA panel previously identified (miR-371a-3p/miR-372-3p/miR-373-3p and miR-367-3p). PATIENTS AND METHODS We performed a pooled analysis of available published raw data where all 4 panel miRNAs had been assessed using pre-amplification PCR technology (4 studies; total 329 patients). Two studies using identical methodology (and identical normalization using endogenous miR-30b-5p) were used in the discovery phase (n = 51 patients: 17 MGCT, 34 controls). The 2 other studies (n = 278 patients: 140 MGCT, 138 controls), which assessed the same test panel but with different normalization approaches (endogenous miR-93-5p, exogenous cel-miR-39-3p), were used for the validation phase. We derived sensitivity, specificity, positive- and negative-predictive-values (PPV/NPV) for the detection thresholds that maximised the Youden Index (YI). RESULTS In the discovery-phase, the YI was 0.97 for miR-371a-3p (sensitivity = 1, specificity = 0.97), 0.71 (miR-367-3p), 0.68 (miR-372-3p), and 0.50 (miR-373-3p). These findings were confirmed in the validation-phase, with YI of 0.75 for miR-371a-3p (sensitivity = 0.90, specificity 0.85), 0.55 (miR-367-3p), 0.47 (miR-372-3p), and 0.51 (miR-373-3p). Importantly, no combination of markers added additional diagnostic benefit to miR-371a-3p alone, in either the discovery or the validation phase. CONCLUSION Quantifying circulating miR-371a-3p alone is sufficient for testicular MGCT diagnosis. PCR measurement of this single miRNA marker will be more cost-effective and easier to interpret, facilitating future incorporation into routine clinical practice.