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Ki-67, IHC with Interpretation

Ki-67, IHC with Interpretation

Test Summary

Ki-67, IHC with Interpretation


Clinical Use

  • Assess tumor cell proliferation (analogous to flow cytometric S-phase fraction)

  • Assess prognosis in patients with bladder, brain, breast, kidney, lung, ovary, prostate, or thyroid malignancy

  • Assist in grading neuroendocrine tumors and assessing prognosis

Clinical Background

Ki-67 is a nuclear non-histone protein that is present at low levels in quiescent cells but is increased in proliferating cells, especially in the G2, M, and latter half of the S phase. Thus, Ki-67 reactivity, defined as percent tumor cells staining positive as measured by immunohistochemical (IHC) staining, is a specific nuclear marker for cell proliferation. Overexpression is frequently seen in a variety of malignant tissues and is associated with worse survival of individuals with bladder,1 brain,2 breast,3,4 kidney,5 lung,6,7 ovary,8 prostate,9 or thyroid10 cancer. In addition, Ki-67 reactivity is included among other parameters in the World Health Organization’s recommended grading system for neuroendocrine tumors of the pancreas and gastrointestinal tract.11 Ki-67 overexpression is associated with worse survival of individuals with a neuroendocrine tumor.10,11

Individuals Suitable for Testing

  • Individuals with bladder, brain, breast, kidney, lung, ovary, prostate, or thyroid malignancy

  • Individuals with neuroendocrine tumors of the pancreas or gastrointestinal tract


  • Immunohistochemical staining

    –  Deparaffinization of FFPE tissue block followed by antigen unmasking

    –  Incubation of tissue sections with mouse monoclonal antibody directed against the C-terminus of Ki-67

    –  Indirect chromogen staining of bound antibody using biotinylated secondary antibody and avidin-conjugated horseradish peroxidase

    –  Percentage of tumor cells that display nuclear staining is reported by a board-certified pathologist

Interpretive Information

Higher Ki-67 reactivity in tumor tissue is associated with adverse outcomes. For breast cancer, prognosis is considered to be favorable with Ki-67 <10%, borderline if 10% to 20%, and unfavorable if >20%.

Results should be interpreted in conjunction with other clinical and laboratory findings.


  1. Tian Y, Ma Z, Chen Z, et al. Clinicopathological and prognostic value of Ki-67 expression in bladder cancer: a systematic review and meta-analysis. PLoS One. 2016;11:e0158891.

  2. Johannessen AL, Torp SH. The clinical value of Ki-67/MIB-1 labeling index in human astrocytomas. Pathol Oncol Res. 2006;12:143-147.

  3. Stuart-Harris R, Caldas C, Pinder SE, et al. Proliferation markers and survival in early breast cancer: a systematic review and meta-analysis of 85 studies in 32,825 patients. Breast. 2008;17:323-334.

  4. Viale G, Giobbie-Hurder A, Regan MM, et al. Prognostic and predictive value of centrally reviewed Ki-67 labeling index in postmenopausal women with endocrine-responsive breast cancer: results from Breast International Group Trial 1-98 comparing adjuvant tamoxifen with letrozole. J Clin Oncol. 2008;26:5569-5575.

  5. Xie Y, Chen L, Ma X, et al. Prognostic and clinicopathological role of high Ki-67 expression in patients with renal cell carcinoma: a systematic review and meta-analysis. Sci Rep. 2017;7:44281.

  6. Shiba M, Kohno H, Kakizawa K, et al. Ki-67 immunostaining and other prognostic factors including tobacco smoking in patients with resected nonsmall cell lung carcinoma. Cancer. 2000;89:1457-1465.

  7. Chirieac LR. Ki-67 expression in pulmonary tumors. Transl Lung Cancer Res. 2016;5:547-551.

  8. Battista MJ, Mantai N, Sicking I, et al. Ki-67 as an independent prognostic factor in an unselected cohort of patients with ovarian cancer: results of an explorative, retrospective study. Oncol Rep. 2014;31:2213-2219.

  9. Tisell LE, Oden A, Muth A, et al. The Ki-67 index a prognostic marker in medullary thyroid carcinoma. Br J Cancer. 2003;89:2093-2097.

  10. Dwivedi SS, Khandeparkar SG, Joshi AR, et al. Study of immunohistochemical markers (CK-19, CD-56, Ki-67, p53) in differentiating benign and malignant solitary thyroid nodules with special reference to papillary thyroid carcinomas. J Clin Diagn Res. 2016;10:EC14-EC19.

  11. Rindi G, Arnold R, Bosman FT, et al. Nomenclature and classification of neuroendocrine neoplasms of the digestive system. In Bosman FT, Carneiro F, Hruban RH, et al. eds. WHO Classification of Tumours of the Digestive System. Lyon, France: IARC Press; 2010:13-14.

  12. Pezzilli R, Partelli S, Cannizzaro R, et al. Ki-67 prognostic and therapeutic decision driven marker for pancreatic neuroendocrine neoplasms (PNENs): A systematic review. Adv Med Sci. 2016;61:147-153.

Content reviewed 04/2017

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