Analysis of SHOX2 methylation as an aid to cytology in lung cancer diagnosis.

BACKGROUND/AIM The Epi proLung® BL Reflex Assay [short stature homeobox gene two methylation assay (SHOX2 assay)] (Epigenomics AG, Berlin, Germany) utilizes quantitative methylation-sensitive real-time polymerase chain reaction (QMSP) for the quantification of methylated short stature homeobox gene two (SHOX2) DNA. In the present study, the diagnostic utility of the SHOX2 assay was tested with regard to cytology for different cytological diagnostic categories to assess whether it can complement the cytological examination and the DNA methylation marker panel targeting the gene promoters of adenomatous polyposis coli 1A (APC), cyclin-dependent kinase inhibitor-2A (p16(INK4A)) and Ras association domain family protein 1 (RASSF1A) regarding lung cancer detection in bronchial aspirates. MATERIALS AND METHODS Prospectively collected DNA from 169 patients (cytological diagnosis: 47 tumor-positive, 56 equivocal and 66 tumor-negative) was analyzed for SHOX2 DNA methylation utilizing QMSP. Patients were followed-up for a period of 11 months maximum. RESULTS When equivocal diagnoses were categorized as tumor-positive, cytology and SHOX2 DNA methylation achieved 72% and 64% sensitivity and 63% and 98% specificity, respectively. SHOX2 DNA methylation identified 66% of the patients with cancer subsequent to a cytological equivocal diagnosis. SHOX2 complements the cytological diagnosis and the methylation marker panel. CONCLUSION The assay could be of use for the improvement of diagnostic accuracy if applied subsequent to equivocal or negative cytology (sensitivity=69%, specificity=98%). Furthermore, the SHOX2 assay can complement a methylation-based marker panel.