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Updated: May 21, 2026
Building Up a High-throughput Screening Platform to Assess the Heterogeneity of HER2 Gene Amplification in Breast Cancers
Published on: December 5, 2017
Her2 negative luminal breast carcinoma and Ki-67 evaluation
Kitty Pavlakis1, Thomas Vrekoussis, Anna Tsipoura
1Pathology Department, National and Kapodistrian University of Athens, Athens, Greece.
Aim:
To determine the degree of inter-observer variability in defining the percentage of Ki-67 immunohistochemical expression in breast carcinoma cases and to investigate the validity of using the cut-point of 14% for the administration of adjuvant treatment in luminal B (Her2 negative) carcinomas.
Materials And Methods:
99 ER, PR positive, Her2 negative breast carcinomas were consecutively selected from the Pathology files of "IASO" Women's Hospital. Ki-67 immunostaining was evaluated by four pathologists from four different institutions.
Results:
Concerning the whole study group, the inter-observer agreement was substantial. Subgroup analysis upon the cases were at least one observer evaluated Ki-67 as being less than 14% showed that the inter-observer agreement was reduced to fair. Further analysis revealed that both below and above the clinicopathological limit of 14%, stands a "grey zone" of about ±7%, in which inter-observer agreement is weak.
Conclusion:
The administration of cytotoxic therapy in ER, PR positive, Her2 negative breast carcinomas featuring a Ki-67 labeling index of around 14, should be considered with caution. Probably decision-making should also take under consideration the whole morphological and biological profile of each tumor.