Evaluation of a miRNA-371a-3p Assay for Predicting Final Histopathology in Patients Undergoing Primary Nerve-sparing Retroperitoneal Lymphadenectomy for Stage IIA/B Seminoma or Nonseminoma

Patients with marker-negative clinical stage IIA/B seminoma or nonseminoma represent a therapeutic challenge, as 20-30% might harbor nonmalignant histologies. MicroRNA 371a-3p (miR371) may represent a biomarker with diagnostic and predictive properties in testicular germ cell tumors (TGCTs). We evaluated the predictive accuracy of this biomarker in identifying the presence or absence of lymph node metastases (LNMs) in clinical stage IIA/B TGCT. In a cohort of 24 consecutive patients with marker-negative clinical stage IIA/B TGCT (n = 15 seminoma, n = 9 nonseminoma) serum miR371 was assessed 1 d before nerve-sparing retroperitoneal lymphadenectomy. Histology revealed metastatic TGCT in 22/24 patients (91.7%), with positive miR371a findings for 20 of these 22 patients with metastases (90.9%). Histology revealed no malignancy in one patient and lymphoma in another, both of whom had negative miR371a findings. One additional patient with pure teratoma and one with a microscopic seminomatous LNM had false-negative miR371a findings. The miR371 assay had sensitivity of 90.9% and specificity of 50%. The positive predictive value was 100.0% and the negative predictive value was 75.0%. According to the data available, miR371a represents a highly reliable, personalized tumor marker for predicting the presence of low-volume retroperitoneal LNMs in marker-negative TGCT. miR371 has potential for inclusion in the diagnostic armamentarium for men with equivocal lymph nodes to facilitate avoidance of unnecessary treatment and the associated toxicity. PATIENT SUMMARY: Our study demonstrates that blood tests for the biomarker miR371 are highly reliable in predicting the presence of lymph node metastases in patients with stage IIA/B testicular cancer. For patients with equivocal findings, use of this test may help in avoiding unnecessary treatment.