SESSION TYPE: Lung Cancer II
PRESENTED ON: Monday, October 22, 2012 at 04:00 PM - 05:30 PM
PURPOSE: NSCLC classification as squamous cell carcinoma (SCC) and non-SCC has clinical utility. With small biopsies, the accuracy of such classification using routine histological examination is ~85%. A new method using reverse transcription-PCR (RTPCR) to classify NSCLC by measuring miR-205 relative to RNU6B and miR-21 for a >95% classification accuracy has been described, but its routine use is limited by the need to use samples with at least 50% tumor content. We sought to simplify this method and to enhance its applicability to small biopsy samples with the use of laser microdissection.
METHODS: RNA levels were measured in quantification cycle values (Cq) or in moles to calculate miR-205 levels relative to RNU6B, or to both RNU6B and miR-21, in 36 non-SCC and 22 SCC resected and formalin-fixed tumor tissues using RTPCR and synthetic small RNA standards (training set). Values for miR-205 in laser microdissected tumor cells from small biopsy samples were similarly determined for a test set of 16 NSCLC cases with known histology after surgical resection using an optimized RNA extraction protocol.
RESULTS: Using the area under curve (AUC) statistic in receiver operator characteristics analysis of our training set, the molar ratio of miR-205 to RNU6B performed as well as Cq values of miR-205 compared to RNU6B and miR-21(AUC = 0.922; 95%CI = 0.853 - 0.991 vs. AUC = 0.943; 95% CI = 0.888 - 0.998; P>0.05). miR-205 levels could be measured in 15/16 samples in the test set; 13/15 (87%) were correctly predicted by either method. For four (31%) of the 13, histology of small biopsies had been deemed indeterminate.
CONCLUSIONS: Our study validates use of microRNA miR-205 level for accurate histological classification in NSCLC.
CLINICAL IMPLICATIONS: Such an assay may be useful to classify NSCLC when histology of small biopsy samples is indeterminable by routine means. Using molarity instead of Cq values, such an assay may be based on just two instead of three analytes and can be transferred to any microRNA expression platform.
DISCLOSURE: The following authors have nothing to disclose: Samjot Dhillon, Santosh Patnaik, Eric Kannisto, Sai Yendamuri
No Product/Research Disclosure InformationRoswell Park Cancer Institute, Buffalo, NY