Effects of conventional neoadjuvant chemotherapy for breast cancer on tumor angiogenesis

The effects of breast cancer conventional chemotherapy on tumor angiogenesis need to be further characterized. Neoadjuvant chemotherapy is an ideal model to evaluate the results of chemotherapy, allowing intra-patient direct comparison of antitumor and antiangiogenic effects. We sought to analyze the effect of neoadjuvant chemotherapy on tumor angiogenesis and its clinical significance in breast cancer. Breast cancer patients (n = 108) treated with neoadjuvant sequential anthracyclines and taxanes were studied. Pre- and post-chemotherapy microvessel density (MVD) and mean vessel size (MVS) were analyzed after CD34 immunohistochemistry and correlated with tumor expression of pro- and antiangiogenic factors (VEGFA, THBS1, HIF1A, CTGF, and PDGFA) by qRT-PCR. Angiogenic measures at diagnosis varied among breast cancer subtypes. Pre-treatment higher MVS was associated with triple-negative subtype and more advanced disease. Higher MVS was correlated with higher VEGFA (p = 0.003), while higher MVD was correlated with lower antiangiogenic factors expression (THBS1, p < 0.0001; CTGF, p = 0.001). Increased angiogenesis at diagnosis (high MVS and glomeruloid microvascular proliferation) and higher VEGFA expression were associated with tumor recurrence (p = 0.048 and 0.009, respectively). Chemotherapy-induced angiogenic response (defined as decreased MVD) was present in 35.2 % of patients. This response correlated with an increase in antiangiogenic factors (THBS1) without changes in VEGFA expression, and it was associated with tumor downstaging, but not with clinical response, pathologic complete response, or prognosis. Global effects of chemotherapy mainly consisted in an increased expression of antiangiogenic factors (THBS1, CTGF), with significant changes neither of tumor VEGFA nor of MVS. Conventionally scheduled neoadjuvant chemotherapy exerts antiangiogenic effects, through an increase in antiangiogenic factors, THBS1 and CTGF, but the expression of VEGFA is maintained after treatment. Better markers of angiogenic response and a better understanding of the cooperation of chemotherapy and antiangiogenic therapy in the neoadjuvant clinical scenario are needed.