New microRNA-based diagnostic test for lung cancer classification.

Abstract

10528 Background: Lung cancer is the leading cause of cancer deaths in the US. Treatment options are determined by tumor subtyping, for which there is lack of standardized, objective, and highly accurate techniques. In 20%-30% of cases significant limitations of tumor quantity and quality prevent full classification of the tumor using traditional diagnostic methods. Using microRNA microarray data generated from over a hundred formalin-fixed, paraffin-embedded (FFPE) primary lung cancer samples, we have identified microRNA expression profiles that differ significantly for the main lung cancer types. Based on these findings, we have developed and validated a microRNA-based qRT-PCR assay that differentiates primary lung cancers into four types: squamous cell carcinoma, non-squamous non-small cell lung cancer, carcinoid and small cell carcinoma. Methods: Over 700 primary tumor samples from different histological types of lung cancer were collected. Samples included FFPE blocks from resection or biopsies and cell blocks from cytology specimens including fine needle aspiration, bronchial brushing and bronchial washing. High-quality RNA was extracted from the samples using proprietary protocols. Expression levels of potential microRNA biomarkers were profiled using microarrays followed by a sensitive and specific qRT-PCR platform. An assay for lung tumors classification using 8 microRNAs on qRT-PCR was developed based on data from 261 samples. This assay was validated on an independent blinded set of 451 cytological and pathological samples. Results: Using the expression levels of 8 microRNAs measured in qRT-PCR, accurate classification of the primary lung tumors into the four main cancer types is obtained. The microRNA-based assay reached an accuracy of 94%. Moreover, cytological samples composed over 50% of the validation set and reached an accuracy of 95%. Conclusions: We present here a new microRNA-based assay for the classification of the four main types of lung cancer based only on the expression of 8 microRNAs. This assay displays very high levels of accuracy for both pathological and cytological samples. The assay comprises a standardized, well-tested and objective tool which can assist physicians in the diagnosis of lung cancer.