Measuring microvascular density in tumors by digital dissection

OBJECTIVE: To develop and validate a digital dissection techniquefor measuring the cross-sectional area of blood vessels in histologic sections of tumors routinely stained with hematoxylin and eosin. STUDY DESIGN: The procedure was first validated in four experimental tumors in rats by comparing the results of the digital dissection technique to functional estimates of the blood volume in the tumors as measured by dynamic, contrast-enhanced magnetic resonance imaging. The method was then tested on a variety of experimental and human tumors. RESULTS: The digital dissection technique yielded results that exactly matched the functional measurements of blood volume infour experimental tumors. Digital dissection of 40 additional tumors in rats showed that 21 infiltrating ductal carcinomas had significantly greater microvascular density (MVD) than 19 benign fibroadenomas (12% vs. 7.9%, P=.028 by two-tailed t test). In 10 human breast carcinomas the MVD was consistently greater than the measurement of blood vessel density as identified by immunohistochemical staining for factor VIII. The between-run coefficients of variation for the MVD assay were 12% (n = 5) for a human breast cancer and 18% (n = 5)for an experimental rat tumor. CONCLUSION: The digital dissection technique is a reproducible, objective and accurate method of measuring MVD in sections of tumors that are routinely stained with hematoxylin and eosin.