Microvessel density and vascular basement membrane immunostaining in tumours of the breast

There is a well established correlation between increased breast tumour microvessel density (MVD) and reduced prognosis. The aims of this study were to investigate (1) if MVD is elevated in regions other than 'hotspots' of node positive versus node negative breast tumours, and (2) to quantitate the percentage of vessels without vascular basement membrane (VBM) components in high vascular density (HVD) and average vascular density (AVD) regions of node positive and node negative breast tumours. Serial sections were immunostained for CD31 and double-stained for CD31 and collagen IV (CollIV), laminin (LAM) or heparan sulphate proteoglycan (HSPG). Microvessel counts were obtained from HVD and AVD regions and the number of VBM positive vessels were expressed as a percentage of total CD31 positive vessels. MVD was significantly higher in both the HVD and AVD regions of node positive compared with node negative breast tumours (t-test; P < 0.03). The average percent vessels positive for CollIV, LAM or HSPG ranged from 18%-45% and did not differ between node positive and negative breast tumours (t-test; P > 0.05). No differences were observed in VBM immunostaining between regions of HVD and AVD (t-test; P > 0.05). These results demonstrate that vascular density is elevated throughout node positive breast tumours, rather than just in 'hotspots', and show that there is no apparent difference in the percentage of VBM-naked vessels in node positive versus node negative breast tumours.