Serum Levels of MicroRNA-371a-3p for Predicting the Histology of Postchemotherapy Residual Masses of Germ Cell Tumours.

Background and objective: Serum levels of microRNA-371a-3p (M371) represent a novel and sensitive biomarker of germ cell tumours (GCTs). This study analysed the utility of M371 to identify viable cancer (VC) in postchemotherapy (pc) residual masses with the underlying goal of avoiding overtreatment.

Methods: A multicentric, prospective diagnostic study was conducted in 180 GCT patients undergoing pc resection of residual masses. A correlation of M371 measurement results with the histological presence of VC in masses was found. A receiver operating characteristic analysis was performed for exploring the performance characteristics of the test.

Key findings and limitations: The sensitivity was found to be 68.9%, specificity 99.3%, area under the curve 0.813, positive predictive value 0.969, and negative predictive value 0.905; sensitivity is significantly associated with the percentage of VC in the mass. In specimens with ≤10% VC, there were 33.3% elevated M371 levels as opposed to 85.7% in specimens with >50% VC. Teratoma and somatic-type malignancy do not express M371. A lack of a central pathological review is a limitation.

Conclusions and clinical implications: The M371 test can identify 68.9% of patients with VC in pc masses. However, cases with <10% VC in the mass may escape detection. Teratoma does not express M371. The test alone cannot correctly identify patients requiring pc surgery, but it may be a tool for scheduling the extent of surgery.

Patient summary: The microRNA-371a-3p (M371) test can identify about two-thirds of patients with viable cancer in residual metastatic masses following chemotherapy for germ cell tumours. Only masses with high percentages of viable cancer cells can be identified, and the histological subtype teratoma remains undetected with the test.