Tissue biopsy alone is diagnostic in less than 10% of cases of metastatic bone disease with an unknown primary tumor. Accordingly, to delineate the neoplastic process in cases of metastatic bone disease, where the primary tumor cannot be determined with conventional modalities, new tools are attractive. Complementary deoxyribonucleic acid cDNA microarrays may be such a tool. Verification and validation of this technology for analysis of specimens ex vivo is mandatory if it is to be used to analyze the complexity of heterogenous biologic tissues. To convey the issues involved in the clinical application of cDNA microarray analysis of tumor specimens ex vivo, a set of experiments analyzing surgically resected human specimens is presented. The specific aims of the analysis were to assess cDNA microarray reproducibility of serial tissue preparations of tumor samples and to confirm that heterogeneity within a given clinical tumor specimen does not preclude this technique as a tool to discern tumor types. Complementary deoxyribonucleic microarray analysis, as it applies to heterogeneous clinical tumor samples in limited numbers, based on preliminary data, seems to be an appropriate but still experimental method for distinguishing tumor types.

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