Detection of recurrences using serum miR-371a-3p during active surveillance in men with stage I testicular germ cell tumours

BACKGROUND: MiR-371a-3p predicts the presence of a macroscopic non-teratomatous germ cell tumour (GCT). We hypothesised that miR-371a-3p can also detect recurrence during active surveillance (AS) of stage I GCT. METHODS: We prospectively collected serum samples of 33 men. Relative expression of serum miR-371a-3p levels was determined at each follow-up visit using real-time quantitative reverse transcription-polymerase chain reaction. RESULTS: Recurrence was detected using standard follow-up investigations in 10/33 patients (30%) after a median of 7 months. Directly after orchiectomy, miR-371a-3p levels were not elevated in any of the 15 patients with available post-orchiectomy samples. However, all ten recurring patients exhibited increasing miR-371a-3p levels during follow-up, while miR-371a-3p levels remained non-elevated in all but one patient without recurrence. MiR-371a-3p detected recurrences at a median of 2 months (range 0-5) earlier than standard follow-up investigations. CONCLUSIONS: MiR-371a-3p levels immediately post orchiectomy are not predictive for recurrences and unfortunately cannot support decision-making for AS vs. adjuvant treatment. However, miR-371a-3p detects recurrences reliably and earlier than standard follow-up investigations. If this can be confirmed in larger cohorts, monitoring miR-371a-3p could replace surveillance imaging in seminomatous GCT and reduce the amount of imaging in non-seminomatous GCT. Earlier detection of disease recurrence may also reduce the overall treatment burden