Tumor stem cells and metastasis

The last decade has seen the emergence of a shift in paradigm in the therapeutic strategies to target cancer. This is based on the existence of a small reservoir of cells within the tumor mass that exhibits the capacity for self-renewal, as well as undergo differentiation to give rise to phenotypically heterogeneous progeny with limited proliferative potential. These stem-like cells likely drive the continued growth of the tumor mass and are capable of disseminating and are subsequently metastasized. Relapse is probably orchestrated by the post-therapy residual drug-resistant "cancer stem" cells that escape treatment. Therefore, the selective targeting of cancer stem cells is supposed to offer radical advances in the treatment and diagnosis of lung cancer. This chapter will discuss the emerging data supporting the validity of this notion and consider the growing evidence that cancer stem cells may contribute to tumor progression, drug resistance, metastasis, and speculates about how taking these cells into consideration may affect the way we treat lung cancer in the future.