Development and evaluation of a virtual microscopy application for automated assessment of Ki-67 expression in breast cancer.
BACKGROUND
The aim of the study was to develop a virtual microscopy enabled method for assessment of Ki-67 expression and to study the prognostic value of the automated analysis in a comprehensive series of patients with breast cancer.


METHODS
Using a previously reported virtual microscopy platform and an open source image processing tool, ImageJ, a method for assessment of immunohistochemically (IHC) stained area and intensity was created. A tissue microarray (TMA) series of breast cancer specimens from 1931 patients was immunostained for Ki-67, digitized with a whole slide scanner and uploaded to an image web server. The extent of Ki-67 staining in the tumour specimens was assessed both visually and with the image analysis algorithm. The prognostic value of the computer vision assessment of Ki-67 was evaluated by comparison of distant disease-free survival in patients with low, moderate or high expression of the protein.


RESULTS
1648 evaluable image files from 1334 patients were analysed in less than two hours. Visual and automated Ki-67 extent of staining assessments showed a percentage agreement of 87% and weighted kappa value of 0.57. The hazard ratio for distant recurrence for patients with a computer determined moderate Ki-67 extent of staining was 1.77 (95% CI 1.31-2.37) and for high extent 2.34 (95% CI 1.76-3.10), compared to patients with a low extent. In multivariate survival analyses, automated assessment of Ki-67 extent of staining was retained as a significant prognostic factor.


CONCLUSIONS
Running high-throughput automated IHC algorithms on a virtual microscopy platform is feasible. Comparison of visual and automated assessments of Ki-67 expression shows moderate agreement. In multivariate survival analysis, the automated assessment of Ki-67 extent of staining is a significant and independent predictor of outcome in breast cancer.
FIMM - Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland. juho.konsti@helsinki.fi.
Juho
J
Konsti
Mikael
M
Lundin
Heikki
H
Joensuu
Tiina
T
Lehtimäki
Harri
H
Sihto
Kaija
K
Holli
Taina
T
Turpeenniemi-Hujanen
Vesa
V
Kataja
Liisa
L
Sailas
Jorma
J
Isola
Johan
J
Lundin
Virchows Arch. 2006 Sep;449(3):288-96
16770642
J Surg Oncol. 1996 Mar;61(3):177-84
8637203
Histopathology. 2007 Oct;51(4):491-8
17711446
J Cancer Res Clin Oncol. 1996;122(11):687-92
8898980
J Clin Pathol. 2008 Mar;61(3):278-82
17693574
Proteomics. 2007 Jun;7(13):2142-50
17549799
BMC Cancer. 2009 May 29;9:165
19476653
J Pathol. 1999 Jan;187(2):207-16
10365096
J Clin Pathol. 1996 Nov;49(11):926-30
8944614
Clin Cancer Res. 2008 Jul 1;14(13):4103-10
18593987
Mod Pathol. 2010 Feb;23(2):251-9
19935641
Breast Cancer Res. 2010;12(4):R56
20663194
Hum Pathol. 2009 Feb;40(2):156-65
18799189
Am J Clin Pathol. 2004 May;121(5):620-30
15151201
Breast Cancer Res Treat. 2008 Aug;110(3):417-26
17912629
Anal Cell Pathol. 1998;16(2):83-93
9692682
Histochemistry. 1993 Oct;100(4):293-6
7506245
Nat Med. 1998 Jul;4(7):844-7
9662379
J Clin Pathol. 2004 Dec;57(12):1288-91
15563669
Cancer. 1995 Dec 15;76(12):2510-7
8625078
Br J Cancer. 2007 May 21;96(10):1504-13
17453008
Histopathology. 2009 Jan;54(2):254-7
19207951
IEEE Trans Inf Technol Biomed. 2004 Jun;8(2):89-96
15217253
Hum Pathol. 1999 Nov;30(11):1314-20
10571511
Pathologica. 1995 Jun;87(3):300-9
8570290
Anal Quant Cytol Histol. 2001 Aug;23(4):291-9
11531144
Psychol Bull. 1968 Oct;70(4):213-20
19673146
JAMA. 2004 Sep 1;292(9):1064-73
15339900
Lab Invest. 2007 Jul;87(7):662-9
17334408
Nat Med. 2002 Nov;8(11):1323-7
12389040
Clin Cancer Res. 1996 Jan;2(1):147-54
9816101
Br J Cancer. 1995 Jan;71(1):146-9
7819031
Breast. 2008 Aug;17(4):323-34
18455396