Categorical meta-analysis of Osteopontin as a clinical cancer marker.

Although extensive literature exists on cancer biomarkers few have found entry into clinical use. In particular, the cancer metastasis gene Osteopontin has been investigated extensively but it has not yet been applied to routine diagnostics. Here, we conduct a meta-analysis of data from the published literature and from RNA microarrays deposited in Oncomine. Osteopontin has been associated with 34 cancers. It is a marker for breast, cervical, colorectal, head and neck, liver, lung, ovarian and prostate cancers, as well as for sarcoma. Osteopontin is overexpressed in the metastases of colorectal cancers, lung cancers and melanomas, but not in ovarian cancer. Further, Osteopontin is indicative of the underlying mechanism of transformation only in certain virally induced tumors, where its function as a TH1 cytokine likely plays important roles. These results refine the value of Osteopontin as a cancer biomarker.