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Original research
Good staining quality ensuring the reproducibility of Ki67 assessment
  1. Yeh-Han Wang1,2,3,
  2. Chiung-Ru Lai4,5,
  3. Huang-Chun Lien6,7,
  4. Chih-Yi Hsu3,4,5
  1. 1 Department of Anatomic Pathology, Taipei Institute of Pathology, Taipei, Taiwan
  2. 2 Institute of Public Health, National Yang-Ming University, Taipei, Taiwan
  3. 3 College of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
  4. 4 Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
  5. 5 School of Medicine, National Yang-Ming University, Taipei, Taiwan
  6. 6 Graduate Institute of Pathology, National Taiwan University, Taipei, Taiwan
  7. 7 Department of Pathology, National Taiwan University Hospital, National Taiwan University, Taipei, Taiwan
  1. Correspondence to Dr Chih-Yi Hsu, Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan; cyhsu{at}vghtpe.gov.tw

Abstract

Aims Although Ki67 labelling index (LI) is a prognostic and predictive marker in breast cancer, its accuracy and reproducibility must be validated before its clinical application. We aimed to evaluate the agreement of Ki67 LI in clinical practice in Taiwan.

Methods We conducted a Ki67 immunohistochemistry (IHC) proficiency test. The participants performed the Ki67 IHC test and measured the Ki67 LI of 10 cases of breast cancer tissue on a microarray slide. The staining quality was centrally reviewed based on the Ki67 staining of the tonsil surface epithelium.

Results Ki67 staining and counting methods are diverse in Taiwan. The reproducibility of Ki67 LI was poor to good (intraclass correlation coefficient: 0.581, 95% CI 0.354 to 0.802). The reproducibility and agreement in the high staining quality group were significantly higher than those in the low staining quality group. The majority of the Ki67 LIs derived from the low staining quality group were underestimated. Different counting methods did not reveal significant differences when determining Ki67 LI with microarray sections.

Conclusions We suggest using the surface epithelium of the tonsil as external control and achieving optimal staining results that consist of a high positive parabasal layer, a low positive intermediate layer and a negative superficial layer. Good Ki67 staining quality can minimise the staining variations among different laboratories, and it is essential for the reproducibility of Ki67 LI.

  • breast cancer
  • immunohistochemistry
  • KI 67
  • quality control

https://doi.org/10.1136/jclinpath-2019-206205

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    Footnotes

    • Handling editor Cheok Soon Lee.

    • Contributors Conceptualisation and design: Y-HW, C-RL, H-CL and C-YH. Data acquisition, analysis and interpretation: Y-HW and C-YH. Manuscript preparation, editing and approval: Y-HW, C-RL, H-CL and C-YH.

    • Funding This study was funded by Taipei Veterans General Hospital (V108C-161) and Taipei Institute of Pathology (TIP-107–001).

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.