Neural cell adhesion molecule expression in renal cell carcinomas: relation to metastatic behavior

Neural cell adhesion molecule (NCAM), a member of the immunoglobulin superfamily, is expressed by a subgroup of renal cell carcinomas (RCCs) and by a limited number of adult organs, including the central nervous system (CNS) and adrenal gland. Because the major function of NCAM is homophilic adhesion between homotypic and heterotypic cells, we hypothesized that NCAM-expressing RCCs should preferentially metastasize to the CNS and adrenal gland. We did a retrospective immunohistochemical analysis of NCAM expression both in 338 primary renal tumors, including 249 conventional RCCs and 31 metastases of conventional RCCs. In primary renal tumors, NCAM was expressed by only 38 (15.2%) conventional RCCs and by no other histological subtypes of renal tumor. This expression correlated with a higher risk of adrenal and CNS metastases (P <0.001). NCAM expression also correlated with tumor size (P <0.001), renal vein involvement (P = 0.02), perirenal invasion (P = 0.02), and Fuhrman grading (P < 0.001). Finally, patients with NCAM-expressing RCCs had a lower survival rate (P = 0.006), especially in the first 2 years after surgery. NCAM expression is of interest both for evaluating the prognosis of patients with conventional RCCs and for determining a subgroup of patients at high risk for adrenal and CNS metastases.