Breast Cancer Stem Cells

Breast cancer is the second most common cancer worldwide and the most frequent among women, and despite several efforts, continues to show a poor prognosis and high mortality. Breast cancer stem cells are a small group of cells among the bulk of the tumor that shows stem cell properties, like self-renewal and immortality. They are believed to be involved in cancer promotion, development, and have been studied as important molecules either for diagnosis or treatment. Although several markers were studied to identify breast cancer stem cells, it stills unclear if the common markers CD44, CD24 and ALDH1 could be used to determine these cells. We will cover in this chapter the possible mechanisms involved in breast cancer stem cells theory, its markers and their potential as prognostic or predictive molecules, in terms of survival and treatment of breast cancer.