title: Bimodality of intratumor Ki67 expression is an independent prognostic factor of overall survival in patients with invasive breast carcinoma.
abstract: Proliferative activity, assessed by Ki67 immunohistochemistry (IHC), is an established prognostic and predictive biomarker of breast cancer (BC). However, it remains under-utilized due to lack of standardized robust measurement methodologies and significant intratumor heterogeneity of expression. A recently proposed methodology for IHC biomarker assessment in whole slide images (WSI), based on systematic subsampling of tissue information extracted by digital image analysis (DIA) into hexagonal tiling arrays, enables computation of a comprehensive set of Ki67 indicators, including intratumor variability. In this study, the tiling methodology was applied to assess Ki67 expression in WSI of 152 surgically removed Ki67-stained (on full-face sections) BC specimens and to test which, if any, Ki67 indicators can predict overall survival (OS). Visual Ki67 IHC estimates and conventional clinico-pathologic parameters were also included in the study. Analysis revealed linearly independent intrinsic factors of the Ki67 IHC variance: proliferation (level of expression), disordered texture (entropy), tumor size and Nottingham Prognostic Index, bimodality, and correlation. All visual and DIA-generated indicators of the level of Ki67 expression provided significant cutoff values as single predictors of OS. However, only bimodality indicators (Ashman's D, in particular) were independent predictors of OS in the context of hormone receptor and HER2 status. From this, we conclude that spatial heterogeneity of proliferative tumor activity, measured by DIA of Ki67 IHC expression and analyzed by the hexagonal tiling approach, can serve as an independent prognostic indicator of OS in BC patients that outperforms the prognostic power of the level of proliferative activity.
authors.affiliation: Department of Pathology, Forensic Medicine and Pharmacology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania. arvydas.laurinavicius@vpc.lt.|National Center of Pathology, Affiliate of Vilnius University Hospital Santariskiu Clinics, P. Baublio 5, LT-08406, Vilnius, Lithuania. arvydas.laurinavicius@vpc.lt.
authors.forename: Arvydas
authors.initials: A
authors.lastname: Laurinavicius
authors.affiliation: PathImage/BioTICLA, Inserm (UMR 1199), University Caen Normandy, Cancer Center F. Baclesse, Caen, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Plancoulaine
authors.affiliation: National Center of Pathology, Affiliate of Vilnius University Hospital Santariskiu Clinics, P. Baublio 5, LT-08406, Vilnius, Lithuania.
authors.forename: Allan
authors.initials: A
authors.lastname: Rasmusson
authors.affiliation: Department of Pathology, Forensic Medicine and Pharmacology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.|National Center of Pathology, Affiliate of Vilnius University Hospital Santariskiu Clinics, P. Baublio 5, LT-08406, Vilnius, Lithuania.
authors.forename: Justinas
authors.initials: J
authors.lastname: Besusparis
authors.affiliation: Department of Pathology, Forensic Medicine and Pharmacology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.|National Center of Pathology, Affiliate of Vilnius University Hospital Santariskiu Clinics, P. Baublio 5, LT-08406, Vilnius, Lithuania.
authors.forename: Renaldas
authors.initials: R
authors.lastname: Augulis
authors.affiliation: National Center of Pathology, Affiliate of Vilnius University Hospital Santariskiu Clinics, P. Baublio 5, LT-08406, Vilnius, Lithuania.
authors.forename: Raimundas
authors.initials: R
authors.lastname: Meskauskas
authors.affiliation: Department of Pathology, Forensic Medicine and Pharmacology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
authors.forename: Paulette
authors.initials: P
authors.lastname: Herlin
authors.affiliation: Department of Pathology, Forensic Medicine and Pharmacology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.|National Center of Pathology, Affiliate of Vilnius University Hospital Santariskiu Clinics, P. Baublio 5, LT-08406, Vilnius, Lithuania.
authors.forename: Aida
authors.initials: A
authors.lastname: Laurinaviciene
authors.affiliation: Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: Abir A
authors.initials: AA
authors.lastname: Abdelhadi Muftah
authors.affiliation: Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: Islam
authors.initials: I
authors.lastname: Miligy
authors.affiliation: Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Aleskandarany
authors.affiliation: Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK.|Histopathology, Nottingham City Hospital University of Nottingham, Nottingham, UK.
authors.forename: Emad A
authors.initials: EA
authors.lastname: Rakha
authors.affiliation: Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Green
authors.affiliation: Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK.|Histopathology, Nottingham City Hospital University of Nottingham, Nottingham, UK.
authors.forename: Ian O
authors.initials: IO
authors.lastname: Ellis
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis / Q000096:biosynthesis*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis; D016016:Proportional Hazards Models
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen
keywords: Automated image analysis; Breast cancer; Digital pathology; Heterogeneity; Hexagonal tiling; Honeycomb; Immunohistochemistry; Ki-67
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