Survivin in esophageal cancer: An accurate prognostic marker for squamous cell carcinoma but not adenocarcinoma

We quantified the expression of survivin, both as mRNA in real-time PCR and protein in immunohistochemistry, in tumor samples of 112 patients with esophageal cancer (56 squamous cell carcinomas and 56 adenocarcinomas). Overall survival of squamous cell carcinoma patients with high survivin mRNA levels was significantly less than that of patients with low survivin mRNA levels (p = 0.0033). Distribution pattern of survivin (nuclear vs. cytoplasmic or mixed) was not correlated to survival, while the extent of immunostaining was significantly correlated to survivin mRNA values (p = 0.016) and had prognostic relevance in univariate analysis (p = 0.0012). Cox's proportional-hazard regression model showed that tumor survivin expression in esophageal squamous cell carcinoma was the most important prognostic factor, independent of tumor stage and other histopathological factors, both as mRNA relative value (p = 0.0259) and protein immunostaining (p = 0.0147). In esophageal adenocarcinoma, survivin expression and pattern of distribution had no prognostic relevance. Thus, quantifying survivin expression provides a prognostic marker only for esophageal squamous tumors.