Background. The LRIG‐1 gene (formerly LIG‐1) encodes a type 1 transmembrane glycoprotein with an extracellular region of 15 leucine‐rich repeats and 3 immunoglobulin‐like domains. LRIG‐1 interacts with ErbB receptors, down‐regulating the downstream signals. Because ErbB signaling is disrupted in cutaneous squamous cell carcinoma (SCC), we examined LRIG‐1 expression in cutaneous SCC.

Objective. To analyze the differential expression of LRIG‐1 and to investigate whether LRIG‐1 is useful as a prognostic indicator in SCC of the skin.

Methods. LRIG‐1 expression in 38 cases of cutaneous SCC patients was examined by immunohistochemistry.

Results. LRIG‐1 expression was highest in well‐differentiated lesions of cutaneous SCC. The cases studied here were categorized into 23 cases (60.5%) of high expression and 15 cases (39.5%) of low expression of LRIG‐1. There was a significant correlation (p= .000018) of LRIG‐1 expression intensity of tumor cells with histologic differentiation of SCC. Furthermore, we found a significant inverse correlation with metastatic rate (p= .02). When the overall survival of SCC patients was statistically compared between high and low LRIG‐1 expression groups, a significant survival benefit for the patients in the former group was found (p= .03).

Conclusion. LRIG‐1 expression is an excellent candidate for a prognostic indicator of cutaneous SCC.

THIS WORK WAS SUPPORTED BY A GRANT‐IN‐AID FOR SCIENTIFIC RESEARCH FROM THE MINISTRY OF EDUCATION, SCIENCE, SPORTS, AND CULTURE OF JAPAN.