Cut-offs for relapse detection in men with stage I testicular germ cell tumors during active surveillance within a prospective multicentre cohort study using either raw or housekeeper normalized miR-371a-3p serum levels.

Purpose: MiR-371a-3p represents a novel liquid biomarker that detects all histologies of germ-cell tumors (GCT) except teratoma. However, it is currently unclear whether miR-371a-3p results obtained directly from RT-PCR (raw Cq) or normalized for housekeeper genes and transformed into the relative quantity (RQ) value should be used and at what cut-off level. The purpose of this research was to evaluate, which values should be used, and a potential cut-off level for relapse-detection to inform subsequent studies.

Materials And Methods: We applied a CE-certified qRT-PCR test to measure miR-371a-3p at each follow-up visit during active surveillance in 34 men with stage I testicular GCT. MiR-371a-3p levels were calculated by the ΔΔ method.

Results: About 18 Patients had pure seminoma and 16 had mixed or nonseminomatous testicular GCT. Recurrences were detected in 10 patients and were correctly identified by both raw and housekeeper-normalized miR-371a-3p serum levels. The raw Cq, with a cut-off value of <28, resulted in only 1 false positive (3%), whereas RQ, with a cut-off value of >15, produced 6 false positive results (17%). Most of these false positive results normalized in subsequent measurements. The RQ approach detected recurrence in 1 patient 6 months earlier than the raw Cq approach.

Conclusion: Our preliminary data suggest that this CE-certified assay, using previously suggested cut-off values, is a promising method for detecting disease recurrence, provided a confirmatory second test is conducted to identify false positive results. To avoid unnecessary scans or overtreatment, we are currently validating this assay and cut-offs in a prospective cohort study.