The specific shapes of capillaries are associated with worse prognosis in patients with invasive breast cancer.

Angiogenesis is considered essential for tumor progression; however, whether histological counting of blood vessel numbers, expressed as microvessel density (MVD), can be a prognostic factor in breast cancer remains controversial. It has been suggested that the specific morphology of blood vessels such as glomeruloid microvascular proliferation (GMP) is associated with clinical parameters. Here, we aimed to clarify the significance of MVD with revised immunohistochemistry and to identify new blood vessel shapes that predict prognosis in breast cancer. Four hundred and eleven primary breast cancer specimens were collected, and the sections were immunohistochemically stained with CD31 (single staining) and CD31 and Collagen IV (double staining). The prognosis of patients was examined based on the MVD value, and the presence of GMP and other blood vessels with other specific shapes. As a result, high MVD value and the presence of GMP were not associated with worse prognosis. By contrast, patients with deep-curved capillaries surrounding tumor cell nests (C-shaped) or excessively branched capillaries near tumor cell nests showed a significantly poor prognosis. The presence of these capillaries was also correlated with clinicopathological parameters such as Ki-67 index. Thus, the morphology of capillaries rather than MVD can be a better indicator of tumor aggressiveness.

Elastin and collagen IV double staining: A refined method to detect blood vessel invasion in breast cancer.

Blood vessel invasion (BVI) is a prognostic indicator in various cancers. Elastic stain, which highlights blood vessel walls, is commonly used to detect BVI. In the breast, however, its diagnostic usefulness is limited because it also highlights some intraductal carcinoma components, which often mimic BVI. In this study, we aimed to improve BVI detection in breast cancer and developed a double staining: Victoria blue for elastin and immunohistochemistry for collagen IV. Collagen IV fibers were retained along the basement membranes of intraductal carcinoma components, whereas they were rearranged or lost in BVI. From these observations, we defined BVI as the presence of tumor cells inside an elastic ring with a rearrangement or loss of collagen IV fibers. Using these criteria, we found BVI in 148 cases (49%) among 304 cases of primary operable invasive breast carcinoma, and the presence of BVI correlated significantly with poor prognosis. By contrast, we detected BVI in 94 cases (31%) or 14 cases (5%) by elastic van Gieson or CD31 immunostaining among the same cases, respectively, with no statistically significant association with prognosis. Thus, elastin and collagen IV double staining facilitates the detection of BVI in breast cancer and is useful to predict prognosis.