Background: Tumor angiogenesis, as assayed by microvessel density, has been proposed as an independent prognostic marker for clinical outcome in breast cancer patients.
Purpose: The present study evaluated the microvessel density assay and assessed its utility, alone and together with the evaluation of other tumor characteristics, in predicting outcome in patients with invasive ductal carcinomas.
Methods: In a blinded design, cases of invasive ductal carcinoma were selected from a registry containing the records of and tumor specimens from 386 breast cancer patients treated at the Massachusetts General Hospital from 1977 through 1982. After the exclusion of ineligible patients and inadequate specimens, 220 patients were included in the study; their median time of follow-up was 11.5 years. Half of these patients (n = 110) were positive for axillary lymph node metastases. Histologic sections of the tumors were stained immunocytochemically for factor VIII, a coagulation protein expressed by blood vessel endothelium, and for p53 protein. Independently, two analysts counted microvessels in three microscope fields selected from separate vascular regions of the tumor. Variability in microvessel scores between analysts and among different fields of the same tumor was summarized by the coefficient of variation. The kappa statistic tested for agreement between the analysts while correcting for chance agreement. The effects of tumor characteristics on metastasis-free survival and overall survival were tested univariately by the Harrington-Fleming rank test procedure. The effect of multiple factors on survival was tested under a Cox multivariate proportional hazards model.
Results: Microvessel count showed considerable variability between the two analysts and among regions within each tumor, with an overall concordance for tumor classification of 73%. Univariate analysis revealed no association between microvessel count and any other tumor or patient characteristic. Multivariate analysis indicated, for these patients, that nodal status and p53 staining predicted metastasis-free survival and that nodal status, estrogen receptor (ER) status and tumor grade predicted overall survival.
Conclusions: Microvessel count showed much variation among different regions of each tumor. It did not predict metastasis-free survival or overall survival. Nodal status was the most powerful criterion to stratify these patients with invasive ductal carcinoma of the breast into different survival groups. Only ER status, tumor grade, and p53 staining had additional prognostic utility for these patients after they had been stratified by nodal status.