Analysis of clinically relevant values of Ki-67 labeling index in Japanese breast cancer patients

Kentaro Tamaki, Takanori Ishida, Nobumitsu Tamaki, Yoshihiko Kamada, Kanou Uehara, Minoru Miyashita, Masakazu Amari, Akiko Tadano-Sato, Yayoi Takahashi, Mika Watanabe, Keely McNamara, Noriaki Ohuchi, Hironobu Sasano

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Background: It has become important to standardize the methods of Ki-67 evaluation in breast cancer patients, especially those used in the interpretation and scoring of immunoreactivity. Therefore, in this study, we examined the Ki-67 immunoreactivity of breast cancer surgical specimens processed and stained in the same manner in one single Japanese institution by counting nuclear immunoreactivity in the same fashion. Methods: We examined 408 Japanese breast cancers with invasive ductal carcinoma and studied the correlation between Ki-67 labeling index and ER/HER2 status and histological grade of breast cancer. We also analyzed overall survival (OS) and disease-free survival (DFS) of these patients according to individual Ki-67 labeling index. Results: There were statistically significant differences of Ki-67 labeling index between ER positive/HER2 negative and ER positive/HER2 positive, ER negative/HER2 positive or ER negative/HER2 negative, and ER positive/HER2 positive and ER negative/HER2 negative groups (all P < 0.001). There were also statistically significant differences of Ki-67 labeling index among each histological grade (P < 0.001, respectively). As for multivariate analyses, Ki-67 labeling index was strongly associated with OS (HR 39.12, P = 0.031) and DFS (HR 10.85, P = 0.011) in ER positive and HER2 negative breast cancer patients. In addition, a statistically significant difference was noted between classical luminal A group and "20 % luminal A" in DFS (P = 0.039) but not between classical luminal A group and "25 % luminal A" (P = 0.105). Conclusions: A significant positive correlation was detected between Ki-67 labeling index and ER/HER2 status and histological grades of the cases examined in our study. The suggested optimal cutoff point of Ki-67 labeling index is between 20 and 25 % in ER positive and HER2 negative breast cancer patients.

Original languageEnglish
Pages (from-to)325-333
Number of pages9
JournalBreast Cancer
Volume21
Issue number3
DOIs
Publication statusPublished - 2014 May

Keywords

  • Breast cancer
  • Cutoff point
  • Estrogen receptor
  • HER2
  • Histological grade
  • Ki-67

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Pharmacology (medical)

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