The Role of Cancer Stem Cells in Breast Cancer Ini- tiation and Progression

Disclosures: The authors indicated no financial relationships. Recent studies have identified a small population of highly tumorigenic cells with stem cell properties in human breast and other solid tumors that are considered to be the source of tumor initiation and maintenance; these cells are re-ferred to as cancer stem cells (CSCs). Preclinical data sug-gest that current breast cancer treatment strategies lead to CSC enrichment, contributing to chemotherapy and radio-therapy resistance, although a strong correlation with clin-ical parameters and prognosis is yet to be established. Importantly, overcoming treatment failure by effective targeting of CSCs may be an appealing approach, poten-tially leading to improved clinical outcomes for patients with breast cancer. Several preclinical studies provide promising results that support this hypothesis. The pur-pose of this review is to summarize the role of CSCs in breast cancer recurrence and resistance and to discuss cur-rent attempts of CSC targeting. The Oncologist 2012;17: 1394–140