A published microarray gene expression database containing data on 174 tumor samples from ten tissues was mined, enabling the identification of classes of genes whose expression correlates significantly with the intractability, or tractability, to therapy of tumors derived from such tissues. As a measure of tractability, the 5-year survival of patients presenting with distant (metastatic) tumors was used. Genes that encode proteins related to cell adhesion, and enzymes involved in metabolic oxidation or reduction, were upregulated in intractable cancers. Genes that encode proteins implicated in the control of DNA transcription were downregulated in the intractable cancers. We describe hypotheses with regard to cell functions that may help in designing new therapeutic modalities, aimed at improving survival of cancer patients.