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Visual assessment of Ki67 using a 5-grade scale (Eye-5) is easy and practical to classify breast cancer subtypes with high reproducibility
  1. Akira I Hida1,
  2. Kenji Bando2,
  3. Atsuro Sugita3,
  4. Toshiharu Maeda4,
  5. Norifumi Ueda5,
  6. Shoichi Matsukage6,
  7. Mamoru Nakanishi6,
  8. Katsumi Kito4,
  9. Tatsuhiko Miyazaki7,
  10. Yuji Ohtsuki8,
  11. Yumi Oshiro1,
  12. Hiromichi Inoue9,
  13. Hidetoshi Kawaguchi9,
  14. Natsumi Yamashita10,
  15. Kenjiro Aogi11,
  16. Takuya Moriya12
  1. 1Department of Pathology, Matsuyama Red Cross Hospital, Matsuyama, Ehime, Japan
  2. 2Department of Pathology, Saiseikai Imabari Hospital, Imabari, Ehime, Japan
  3. 3Pathology Division, Ehime University Hospital, Toon, Ehime, Japan
  4. 4Department of Pathology, Ehime Prefectural Central Hospital, Matsuyama, Ehime, Japan
  5. 5Saiseikai Saijo Medical Center, Saijo, Ehime, Japan
  6. 6Division of Pathology & Laboratory Medicine, Uwajima City Hospital, Uwajima, Ehime, Japan
  7. 7Pathology Division, Gifu University Hospital, Gifu, Japan
  8. 8Division of Pathology, Matsuyama-shimin Hospital, Matsuyama, Ehime, Japan
  9. 9Department of Breast Surgery, Matsuyama Red Cross Hospital, Matsuyama, Ehime, Japan
  10. 10Division of Clinical Biostatistics, Center for Clinical Research, National Hospital Organization Shikoku Cancer Center, Matsuyama, Ehime, Japan
  11. 11Department of Breast Oncology, National Hospital Organization Shikoku Cancer Center, Matsuyama, Ehime, Japan
  12. 12Department of Pathology 2, Kawasaki Medical School, Kurashiki, Okayama, Japan
  1. Correspondence to Dr Akira I Hida, Department of Pathology, Matsuyama Red Cross Hospital, 1 Bunkyo, Matsuyama, Ehime 790-8524, Japan; gbears{at}matsuyama.jrc.or.jp

Abstract

Aims Personalised breast cancer therapy requires pathological characterisation of tumours. The proliferative index, based on Ki67, is pivotal, but a standard method has not been established. Here we look for an easy and practical way to evaluate Ki67.

Methods Immunohistochemical staining of estrogen receptors, progesterone receptors, HER2 and Ki67 (MIB-1) was performed on resected specimens from 406 primary invasive ductal carcinomas. Ki67 labelling index (LI) from manual counting was compared with visual assessment using a 5-grade scale (Eye-5). Next, 10 pathologists evaluated 100 samples with marked hot spots by using Eye-5. Another 100 samples without marking were also assessed by eight pathologists. One year later, two pathologists reviewed 222 cases with Eye-5. Prognosis was analysed among estrogen receptor-positive cases with postoperative endocrine therapy.

Results Eye-5 showed good correlation to LI. All 136 cases of score 4–5 had LI >20% and all 56 cases of score 1 had LI<20%, which means that manual counting was not necessary for about half of the cases. Interobserver and intraobserver variability was low even when a hot spot was not fixed. Eye-5 also correlated with histological grade and lymph node metastasis. Combining Eye-5 and histological grade created a new algorism to predict LI, which allows 80% of all cases (74% of luminal cases) without manual counting. Cases of Eye-5 score 1–2 had significantly better survival than score 3–5.

Conclusions Visual assessment of Ki67 by a 5-grade scale (Eye-5) is fast, easy, and reliable with acceptably low interobserver and intraobserver variability. Eye-5 can replace LI in many luminal tumours, and is a strong candidate as a standard method of evaluating Ki67.

  • BREAST CANCER
  • BREAST PATHOLOGY
  • TUMOUR BIOLOGY

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