Ki-67 expression in breast cancer tissue microarrays: assessing tumor heterogeneity, concordance with full section, and scoring methods
American Journal of Clinical Pathology, 2017•academic.oup.com
Objectives Ki-67 has been proposed to be used as a surrogate marker to differentiate
luminal breast carcinomas (BCs). The purpose of this study was to determine the utility of
and best approaches for using tissue microarrays (TMAs) and Ki-67 staining to distinguish
luminal subtypes in large epidemiology studies of luminal/human epidermal growth factor
receptor 2 (HER2)–negative BC. Methods Full-section and TMA (three 0.6-mm cores and
two 1.0-mm cores) slides of 109 cases were stained with Ki-67 antibody. We assessed two …
luminal breast carcinomas (BCs). The purpose of this study was to determine the utility of
and best approaches for using tissue microarrays (TMAs) and Ki-67 staining to distinguish
luminal subtypes in large epidemiology studies of luminal/human epidermal growth factor
receptor 2 (HER2)–negative BC. Methods Full-section and TMA (three 0.6-mm cores and
two 1.0-mm cores) slides of 109 cases were stained with Ki-67 antibody. We assessed two …
Objectives
Ki-67 has been proposed to be used as a surrogate marker to differentiate luminal breast carcinomas (BCs). The purpose of this study was to determine the utility of and best approaches for using tissue microarrays (TMAs) and Ki-67 staining to distinguish luminal subtypes in large epidemiology studies of luminal/human epidermal growth factor receptor 2 (HER2)–negative BC.
Methods
Full-section and TMA (three 0.6-mm cores and two 1.0-mm cores) slides of 109 cases were stained with Ki-67 antibody. We assessed two ways of collapsing TMA cores: a weighted approach and mitotically active approach.
Results
For cases with at least a single 0.6-mm TMA core (n = 107), 16% were misclassified using a mitotically active approach and 11% using a weighted approach. For cases with at least a single 1.0-mm TMA core (n = 101), 5% were misclassified using either approach. For the 0.6-mm core group, there were 33.3% discordant cases. The number of discordant cases increased from 18% in the group of two cores to 40% in the group of three cores (P = .039).
Conclusions
Ki-67 tumor heterogeneity was common in luminal/HER2– BC. Using a weighted approach was better than using a mitotically active approach for core to case collapsing. At least a single 1.0-mm core or three 0.6-mm cores are required when designing a study using TMA.
Oxford University Press