Expression and clinical significance of lung-specific X protein mRNA in bronchial brushing specimens from patients with or without lung cancer

Background and objective: The aim of this study was to evaluate the diagnostic utility of lung-specific X protein (LUNX) mRNA expression in bronchial brushing specimens from patients with lung cancer. Methods: LUNX mRNA levels were assessed by performing RT-PCR on liquid-based cytology bronchial brushing specimens from patients with lung cancer (n = 104) or benign lung disease (n = 91). Results: LUNX mRNA expression was significantly more frequent in patients with all carcinomas, squamous cell carcinomas, adenocarcinomas, as well as patients with central, peripheral and diffuse carcinomas (P < 0.01), and non-small cell lung carcinomas (P < 0.05) compared with patients with benign disease. The diagnostic performance of RT-PCR analysis of LUNX mRNA was significantly better than that of cytology in terms of sensitivity (93.3 +/- 4.8% vs 64.4 +/- 9.2%), negative predictive value (91.6 +/- 6.0% vs 71.1 +/- 7.9%) and accuracy (88.7 +/- 4.4% vs 81.0 +/- 5.5%), whereas specificity (83.5 +/- 7.6%) and positive predictive value (86.6 +/- 6.3%) were lower than those of cytology (100%). Conclusions: Liquid-based cytology and RT-PCR can be performed to detect LUNX mRNA expression in bronchial brushing specimens, and this technique may be a useful adjunct to cytological diagnosis of lung cancer. The sensitivity of the technique was greater than that of cytology but its lower specificity should be taken into account.