Background: L1 (CD171) is a neuronal cell adhesion molecule that is be expressed in colorectal cancer cells with invasive potential. The aim of the present study was to determine L1 expression in tumor samples and correlate expression with outcome after surgery.
Methods: A tissue microarray (TMA) was constructed from 375 patients that were surgically treated for colorectal cancer, among them 373 primary colorectal cancers, 129 nodal, 49 liver metastases and 25 local relapses. Slides were analyzed by immunohistochemistry with a monoclonal mouse antibody against L1 by peroxidase method.
Results: 48 (13%) of 375 samples examined were L1 positive. Analysis of tumor-specific and overall survival of 247 completely resected colorectal cancer patients presenting without metastasis at initial diagnosis revealed a significant worse survival for L1 positive patients by log-rank test (p<0.05). Multivariate Cox regression analysis revealed an independent prognostic impact of L1 (p<0.05).
Conclusion: The results show that L1, expressed in a minority of colorectal cancer patients, is a strong prognostic indicator after complete surgical resection. Future studies should focus on the detection of L1 in serum samples to examine its usefulness as a peripheral tumor marker.