Stem cells and cancer in the aerodigestive tract

Recently, there have been significant advances in our knowledge of stem cells found in epithelial tissues. In particular, novel stem cell markers have been identified that for the first time identify multipotential cells; a required characteristic of a stem cell. The scarcity of cancer stem cells has been questioned. Current dogma states that they are rare, but novel research has suggested that this may not be the case. Here I review the latest literature on stem cells, particularly so-called cancer stem cells present in tumours of the respiratory tract and colorectum. I discuss current thinking on how stem cells develop into cancer stem cells, how they protect themselves from doing so, and whether cancer stem cells express unique markers that can be used to detect them. Finally, I attempt to put into perspective these latest advances in cancer stem cell biology from the viewpoint of perhaps more effective cancer therapies.