Sox2 Protein Expression is an Independent Poor Prognostic Indicator in Stage I Lung Adenocarcinoma

Abstract

Many patients with stage I non-small cell lung carcinoma will develop recurrence following surgical excision. Sox2 is a marker of embryonic stem cell pluripotency that is associated with aggressive tumor behavior and is expressed in a subset of lung adenocarcinomas. We hypothesized that Sox2 expression may provide prognostic information in early stage lung adenocarcinomas. We evaluated formalin-fixed paraffin embedded tissue from 104 stage I lung adenocarcinomas resected between 1997 and 2000. Sox2 expression was analyzed by immunohistochemistry and compared to clinicopathologic features, time-to-progression (TTP) and overall survival (OS). Sox2 expression was detected in 50% of cases and was more frequent in tumors from older and male patients but not significantly associated with smoking status, tumor stage, grade, or histologic subtype. Compared to Sox2-negative tumors, Sox2 expression predicted a shorter TTP (49% versus 82% at 5 years; P = 0.0006) and shorter OS (54% versus 79% at 5 years; P = 0.004). By multivariate analysis, Sox2 expression predicted a greater risk of progression among men (hazard ratio [HR] 5.6; 95% CI 2.3 to 13.8) and women (HR 2.1; 95% CI 0.8 to 5.7). Sox2 expression was associated with significantly shorter OS among men (HR 2.5; 95% CI 1.2 to 5.1), but not in women. Sox2 appears to be an independent predictor of poor outcome in stage I lung adenocarcinomas and may help stratify patients at increased risk for recurrence.