Quantitation of Endothelial Progenitor Cells as Markers of Tumor Angiogenesis in Breast Cancer

Accumulating evidence emphasizes the emerging role of circulating endothelial cells (CECs)
and endothelial progenitor cells (EPCs) in tumor angiogenesis as surrogate markers and in
the efficacy of anti-angiogenic therapies in breast cancer (22-27). Furstenberger et al.
(22) reported that CECs were significantly elevated in breast cancer patients and decreased
during chemotherapy (anthracycline and/or taxane based). However, EPCs (CD34+/VEGFR-2+) as
well as their progenitor cell population CD133+/CD34+ and the population of CD34+ stem cells
increased together with VEGF, erythropoietin and angiopoietin-2 levels. Their data suggest
that chemotherapy reduces mature CECs, while mobilizing the EPC population. Using real-time
PCR and flow cytometry, they also showed that CD146, an endothelial cell specific antigen,
was significantly increased in newly diagnosed breast cancer patients compared to healthy
controls (23). Other studies also reported increased circulating EPCs in breast cancer
patients in addition to CECs (24,25). In another study, circulating EPCs were not increased
in cancer patients despite the high plasma VEGF levels (26). Another interesting aspect is
that Mancuso et al (27) showed that CEC kinetics correlate with progression-free and overall
survival but not circulating progenitor cells in metastatic breast cancer.

Inclusion Criteria:

- Diagnosis of metastatic breast cancer(stage IV), or women with a history of Stage I
or II breast cancer disease who are currently disease free Women greater than or
equal to 18 years of age Ability to understand and the willingness to sign an
informed consent

Exclusion Criteria:

- Chemotherapy, radiation, or surgery within the past 4 weeks.