The ability of epithelial neoplasms to evade both hormonal and cytotoxic therapies is self-evident as the common carcinomas (lung,stomach,breast,colon and prostate) at their metastatic stage are rarely curable with current therapies.Though the precise reasons for incurability are debated,virtually all agree that tumor genetic heterogeneity makes eradication of the tumor difficult given ‘Darwinian\' selection processes that are associated with the emergence of drug-resistant cellular clones.