Prognostic significance of MCM7 expression in the bronchial brushings of patients with non-small cell lung cancer (NSCLC).

PURPOSE: To identify potential biomarkers for the prognosis of non-small cell lung cancer (NSCLC) patients by using bronchial brushing specimens.

METHODS: The expression of MCM7, Ki67 and EGFR was evaluated in 494 NSCLC tissues and 174 bronchial brushings using immunohistochemical and immunocytochemical techniques. Associations between protein expression and clinico-pathologic parameters were assessed, and the impact on overall survival (OS) was analyzed.

RESULTS: High expression of MCM7, Ki67 and EGFR was detected in 33.3%, 23.5% and 12.7% of tissues and in 52.4%, 52.7% and 20.6% of bronchial brushings, respectively. Expression of MCM7 and Ki67 was associated with squamous cell carcinoma (SCC) in both tissues and bronchial brushings (MCM7: P = 0.0007, 0.00003; Ki67: P < 0.00001, 0.00001). Overexpression of MCM7 in tumor tissues was detected more frequently in poorly differentiated tumors (P = 0.0120) and non-bronchioloalveolar carcinomas (non-BACs) (P = 0.0238). EGFR overexpression was observed in tissues of larger tumors (P = 0.00004) and in bronchial brushings at later stage (P = 0.0262). Kaplan-Meier curves indicated that patients with overexpression of MCM7 or Ki67 had a poorer OS compared to those with low expression for all stages (P < 0.00001, 0.0233) and early-stages (P < 0.00001, 0.0032). In particular, the patients with MCM7 overexpression in bronchial brushings had a poorer prognosis (P = 0.0045). Multivariate Cox regression analysis showed that MCM7 was an independent prognostic indicator both in tissue samples and bronchial brushings.

CONCLUSIONS: Our data suggest that MCM7 and Ki67 in tumor tissues may be potential markers of a poor prognosis for NSCLC patients. MCM7 in bronchial brushings also showed an independent prognostic value, which may be useful when biopsies are unavailable.