Reproducibility of microvessel counts in breast cancer specimens

Assessment of tumour vascularity in core biopsy specimens may be a useful p redictor of response to primary therapy. This study addresses practical met hodological issues regarding accuracy of tumour vascularity assessments in different breast cancer specimens. Issues addressed in the study are Variat ion caused by (i) inherent observer Variation in the method, (ii) tumour he terogeneity and (iii) previous surgical manipulation of tumours. Microvesse l counts were performed by two observers on separate occasions and by two d ifferent observers. Counts were performed on core biopsies and tumour secti ons taken simultaneously (n = 16) and with an intervening time interval (n = 21). In addition core biopsies were obtained from the same tumour on two separate occasions (n = 10), A highly significant correlation was found in counts performed by the same observers at different times and between two d ifferent observers. No significant correlation was found in counts of core biopsies and tumour sections taken either simultaneously or subsequently. N o correlation was found between counts of sequential core biopsies. Study f indings suggest that, although microvessel counts may be assessed reproduci bly by the same and different observers, counts performed in core biopsies do not accurately reflect those of overall tumour, limiting their potential as predictive or prognostic markers. (C) 1999 Cancer Research Campaign.