Abstract

In spite of the advances in our knowledge of cancer biology, most cancers remain not curable with present therapies. Current treatments consider cancer as resulting from uncontrolled proliferation and are non‐specific. Although they can reduce tumour burden, relapse occurs in most cases. This was long attributed to incomplete tumour elimination, but recent developments indicate that different types of cells contribute to the tumour structure, and that the tumour's cellular organization would be analogous to that of a normal tissue, with a main mass of differentiating cells sensitive to anti proliferative agents, together with a small percentage of quiescent, resistant stem cells responsible for replenishing the tumour: the Cancer Stem Cells (CSCs). Anti‐CSCs targeted therapeutic agents would prevent tumour regeneration. New mouse models tailored to exploit this novel concept will be critical to develop CSC‐based anti‐cancer therapies. Here we review the biological basis and the therapeutic implications of the stem‐cell model of cancer. BioEssays 29:1269–1280, 2007. © 2007 Wiley Periodicals, Inc.