Abstract 786: Vascularity and vascular maturity in breast cancer: a comparative analysis of the different molecular subtypes

Abstract

Abstract Currently, angiogenesis inhibitors lack considerable activity and did not result in survival advantage in breast cancer. The goal of this study is to evaluate vasculature in terms of vascularity and vascular maturity among breast cancer subtypes. Archived tumor samples for breast cancer patients were retrieved from Pathology Department at Royal Medical Services in Jordan. Tissue sections were stained for the expression of basement membrane laminin using immunohistochemical analysis. Endothelial cell and pericyte were identified and counted based on the shape of the nuclei as visualized with DAPI stain. Demographic, clinical, and pathological data were retrieved from patient medical records at time of diagnosis. Vascularity was obtained by counting the number of blood vessels and maturity of blood vessels is represented by the ratio of the average number of endothelial cell to average number of pericytes. A total of 60 patients were enrolled in this study in which 34 patients (56.7%) have hormone-dependent disease, 14 patients (23.3%) determined to have HER2-positive disease, and 12 cases (20.0%) were classified as triple-negative. Results showed a significant difference for the mean number of blood vessels (p=0.008) and endothelial cell to pericyte ratio (p=0.000) among the different molecular subtypes of breast cancer. Post hoc analysis indicated statistically significant difference in mean number of blood vessels between hormone- dependent and HER2-positive tumors (p=0.015). In addition, ratio of endothelial cells to pericytes was significantly different between hormone-dependent cases and each of HER2-positive and triple-negative cases (p=0.000 and 0.014, respectively). Size of tumor was significantly correlated to endothelial cell to pericyte ratio for the population examined (r=0.345, p=0.007). A significant correlation was found between the number of blood vessels and number of involved lymph nodes among all patients (r=0.271, p=0.038). Independent samples t–test analysis comparing mean number of blood vessels and endothelial to pericyte ratio according to hormone receptor status showed significant difference between hormone receptor negative and positive cases for both estrogen and progesterone receptors (p<0.05). No significant difference was found for the vascular parameters tested according to tumor stage, grade, and lymphovascular invasion (p>0.05). Collectively, these findings showed that the degree of tumor vascularity and vascular maturity are not uniform among breast cancer subtypes. Vascular maturity was remarkably higher for hormone-dependent breast tumors compared to both HER2-positive and triple-negative cases. It is critical that a careful assessment of tumor vasculature is being considered in breast cancer patients in order to determine responsiveness to chemotherapy and anti-angiogenic treatment among the different molecular subtypes. Citation Format: Nehad M. Ayoub, Ahmed Y. Al Husban, Hussein M. Al Husban, Abdul Rahman N. Al Khatib, Alaa O. Al-Mesleh, Ekhlas A. Al-Majali. Vascularity and vascular maturity in breast cancer: a comparative analysis of the different molecular subtypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 786. doi:10.1158/1538-7445.AM2017-786