Caveolin 1 expression independently predicts shorter survival in oligodendrogliomas

Caveolin 1 (cav-1) is the basic component of the flask-shaped membrane microdomains known as caveolae that are involved in various cell functions. Caveolin 1 can be overexpressed in tumors, suggesting a proneoplastic role, or it can be downregulated. We previously reported that cav-1 expression increases with tumor grade in astrocytomas. Here, we studied cav-1 immunoreactivity in brain tumors with an oligodendroglial component to determine the prognostic value of cav-1 expression and to correlate it with 1p/19q deletions. Fifty-four oligodendrogliomas, 26 mixed oligoastrocytomas, and 7 glioblastomas with an oligodendroglial component were assessed for cav-1 expression by immunohistochemistry and for 1p/19q status by fluorescence in situ hybridization. Caveolin-1 was detected in a minority of cases (22%) and was associated mostly with Grade III mixed oligoastrocytomas and glioblastomas with an oligodendroglial component; cav-1 expression was significantly correlated with the absence of a 1p/19q deletion (p = 0.0002). In the 63 cases in which survival data were available, cav-1 expression was also significantly associated with shorter survivals, whereas 1p/19q deletion was associated with longer survivals. Among high-grade tumors, cav-1 expression was the only factor that retained a statistical significance after multivariate analysis for the prediction of a short survival (p < 0.015). These data are the first evidence that cav-1 immunohistochemistry is an independent prognostic marker in tumors with an oligodendroglial component regardless of the 1p/19q status.