Circulating and disseminated tumor cells in the clinical management of breast cancer patients: unanswered questions.

Breast cancer is the most common cancer in women. Although survival rates have improved with the use of new therapeutic agents, many issues remain unresolved and new predictive and prognostic factors are needed in clinical practice. Several studies have suggested a prognostic and predictive role for circulating and disseminated tumor cells in metastatic disease and adjuvant treatment. Because of recent technological advances, oncologists have gained a new perspective on this disease. Circulating tumor cells could be both a new tumor marker as well as a tool to gain novel insight into the natural history of this neoplastic disease.