Prognostic impact of tumor IL-6 expression after preoperative chemoradiotherapy in patients with advanced esophageal squamous cell carcinoma.

Elevated serum interleukin-6 (IL-6) levels have been associated with tumor progression and poor prognosis in patients with esophageal carcinoma. The purpose of the present study was to clarify such a relationship in patients with esophageal squamous cell carcinoma with a focus on the possible influence of chemoradiotherapy (CRT) on tumor IL-6 expression. Data regarding 41 patients with clinical T3-T4 tumors who underwent induction chemoradiotherapy followed by surgery (CRT group) and 60 patients with clinical T1-T4 tumors who underwent surgery alone (Surgery group) between 2001 and 2010, were retrospectively analyzed. Tumor IL-6 expression in resected specimens was evaluated by immunohistochemistry. Tumor IL-6 expression was detected in patients with advanced tumors in the Surgery group (21.1% in p(stage) III-IV vs. 0.2% in p(stage) I-II; 27.8% in pT3-4 vs. 0% in pT1-2), and also correlated with primary tumor progression and surgical curability in the Surgery group. In addition, patients with IL-6-positive tumors had significantly shorter overall survival than those with IL-6-negative tumors in the CRT group, and tumor IL-6 expression had an independent prognostic value in multivariate analysis, whereas no significant difference in overall survival was observed between patients with IL-6-positive and those with IL-6-negative tumors in the Surgery group. These results indicate that pre-treatment tumor IL-6 expression correlates with primary tumor progression, and CRT-induced tumor IL-6 expression predicts poor prognosis.