Aims Tumour microvessel density (MVD) is assessed by counting vessels in the most vascularised tumour region, the vascular hot spot. Current uncertainty regarding the prognostic role of MVD in breast cancer could, in part, be explained by variations in field area size for MVD assessment. We aimed to identify the field area size that provides the most accurate prognostic information in breast carcinoma.
Methods MVD was assessed in 212 tumours. von Willebrand factor positively stained vessels were counted in 10 consecutive visual fields in vascular hotspots. The 10 visual fields in the original counting sequence (MVD-Consecutive) were sorted from highest to lowest vessel count (MVD-Decreasing), and randomly (MVD-Random). After adding counts from one visual field at a time, mean MVD was calculated for each cumulative field area. The prognostic informativeness of each field area and sorting strategy were compared.
Results Median MVD decreased with increasing field size for MVD-Decreasing and MVD-Consecutive. A 0.35 mm2 total field area comprising only the highest vessel counts provided the most accurate prognostic information (MVD-Decreasing, HR for breast cancer death 1.06 per 10 vessels/mm2 increase, 95% CI 1.03 to 1.10). MVD-Decreasing gave more accurate prognostic information than MVD-Consecutive and MVD-Random, with decreasing prognostic informativeness with increasing field area.
Conclusions Median MVD and its prognostic informativeness decreased with increasing field area. Assessing MVD in a carefully selected small field area of 0.35 mm2 provides the most accurate prognostic information. This could facilitate the implementation of MVD assessment in breast cancer.
- breast cancer
- breast pathology
- blood vessels
- tumour biology
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Handling editor Dhirendra Govender.
Contributors All authors actively contributed to the paper, and take responsibility and accountability for the accuracy and integrity of the work. AMB: study design; selection of vascular hot spots; interpretation of results; writing the article. MRK: study design; selection of vascular hot spots; MVD assessment; statistical analyses; interpretation of results; writing the article. SO: study design; guidance in statistical analyses; interpretation of results; writing the article. HGR: interpretation of results; writing the article.
Funding This study received financial support from the Norwegian University of Science and Technology, Trondheim, Norway.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The regional committee for medical and health research ethics approved the study, including the dispensation from the requirement of patient consent (REK Midt-Norge, reference number: 2009/836).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement There are no additional unpublished data pertinent to this study.
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