The addition of genetic analysis to the evaluation of thyroid FNA samples improves diagnostic accuracy of indeterminate thyroid nodules. This study evaluated the ability of interdependent pairwise microRNA expression analysis to further improve the diagnostic performance of a multiplatform test (MPTX), which for this study will be referred to as MPTXv1.
A novel Benign/Malignant microRNA (miRNA) pairwise expression profiler (MPTXv2) was developed and validated in a fully blinded cohort (n=197) from a previous retrospective validation study for MPTXv1. This new analysis revealed that MPTXv2 provides clinically and statistically superior risk stratification. Using the MPTXv2, a Positive or Negative result was provided in 154 out of 178 (86%) ITN, while in the previous analysis (MPTXv1) a Positive or Negative result was provided in 128 out of 178 (52%). This improvement is largely due to an increase in the number of true negative results and reduction on false positive results with a subsequent improvement in the specificity and PPV, while preserving a high sensitivity and NPV. The Benign/Malignant Profiler (MPTXv2) was particularly effective in estimating the malignant potential of ITN with no mutation or with RAS-like mutations.
In comparing MPTXv1 to MPTXv2, the ROC AUC increased from 0.85 to 0.97 (p<0.001), and the diagnostic accuracy at the positive threshold increased significantly (p<0.05) from 83% (CI = 76-88) to 93% (CI = 89-96). The significant improvement in the ROC AUC and the diagnostic accuracy was due to a strong statistical trend for improvement in specificity at the positive threshold. The addition of miRNA pairwise expression profiling (MPTXv2) resulted in optimized risk stratification of nodules with RAS-like mutations, minimally invasive follicular carcinomas, low-grade PTC, and Hürthle cell predominant (HCP) nodules – providing significant improvement in test accuracy and the highest NPV and PPV of commercially available tests.