L1 cell adhesion molecule as a predictor for recurrence in pulmonary carcinoids and large-cell neuroendocrine tumors.

Pulmonary neuroendocrine tumors are a distinct subset of neoplasms with indolent to aggressive behavior. This study was conducted to evaluate the prognostic role of L1 cell adhesion molecule (L1CAM) in pulmonary neuroendocrine tumors. We retrospectively analyzed L1 expression in 55 cases of completely resected carcinoids and large-cell neuroendocrine carcinomas, by the immunohistochemistry with monoclonal antibody A10-A3 against human L1. L1 immunoreactivity was detected in 34 (61.8%) of 55 specimens. There was a significant correlation between L1 expression and the World Health Organization classification of this tumor (Spearman rank correlation, rho=0.60, p<0.001). With median follow-up of 52.0 months, the 5-year survival rate for patients with low expression of L1 (<20% of tumor cells stained) was significantly better compared with those with high expression of L1 (82.6% vs. 43.7%, p=0.005). L1 was also a significant independent predictor of disease-free survival, and patients with high L1 expression have a higher risk for recurrence compared with those with low L1 expression (hazard ratio, 3.0; 95% confidence interval, 1.2-8.3; p=0.034). L1 expression is significantly associated with aggressiveness and further studies with larger samples are needed to validate potential prognostic value for pulmonary neuroendocrine tumors.