Background: Luminal-type breast cancer is divided into types A and B, depending on the Ki-67 labeling index (LI). However, the area at which Ki-67 is measured and the choice of specimen greatly affects the results. The aim of the present study was to evaluate the Ki-67 LI variability using different measurement methods and specimens. We also evaluated how the chemotherapy indication changed for luminal-type breast cancer using the different measurements.
Materials and methods: The Ki-67 levels in 87 patients with breast cancer were assessed, and the Ki-67 LI was calculated. Five measurement sites were randomly selected, including the most densely labeled areas (hot spots) in both core needle biopsy (CNB) and surgical specimens.
Results: The intraclass correlation coefficient of the CNB and surgical specimens was 0.91 and 0.95, respectively. If the hot spot was used, the correlation coefficient (CC) between the CNB and surgical specimens was 0.635. If the average score was used, the CC was 0.730. If the average score was used, the CNB specimens indicated that 49 patients had a high Ki-67 LI, and 48 patients had a high Ki-67 LI using surgical specimens. If the hot spot was used, 60 patients using the CNB specimens and 58 patients using the surgical specimens had a high Ki-67 LI. If the average score was used, 17 patients were identified as being in different groups, and if the hot spot was used, 16 patients were identified as being in different groups, depending on the specimens that were used.
Conclusion: The results differed according to the method and specimen type that was used.
Keywords: Breast cancer; Hot spot; Ki-67; Luminal type; Varability.
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