Serum endostatin and bFGF as predictive factors in advanced breast cancer patients treated with letrozole

Introduction. To investigate the value of baseline serum levels of VEGF, bFGF, endostatin and their ratio as predictive factors of response to endocrine therapy in patients with metastatic breast cancer (MBC) and positive ER treated with letrozole after tamoxifen failure. Materials and method. The serum levels of endostatin, VEGF and bFGF were determined in post-menopausal patients with progressing MBC from serum samples obtained before initiation of letrozole. The relation between serum angiogenic factor levels and TTP was investigated. Results. Seventy-six patients (45.2%) presented a high endostatin level (>24.6 ng/ml), 40% low bFGF levels (0 pg/ml) and 50.4% low VEGF (≤187 ng/ml). With a median follow-up of 22 months, the median TTP was 12.3 months. Median TTP was worse in patients with high endostatin concentration as well as in the low bFGF group, but was not affected when VEGF was considered. When the two factors were combined, the median TTP of patients with endostatin >24.6 ng/ml and bFGF equal 0 pg/ml was 9.5 months versus 19.5 months in patients with endostatin ≥24.6 ng/ml and bFGF>0 pg/ml. Conclusions. The baseline levels of bFGF and endostatin are predictive factors of efficacy in patients with MBC treated with letrozole and can select groups with different TTP. © FESEO 2006.