Free digital image analysis software helps to resolve equivocal scores in HER2 immunohistochemistry.
Evaluation of human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) is subject to interobserver variation and lack of reproducibility. Digital image analysis (DIA) has been shown to improve the consistency and accuracy of the evaluation and its use is encouraged in current testing guidelines. We studied whether digital image analysis using a free software application (ImmunoMembrane) can assist in interpreting HER2 IHC in equivocal 2+ cases. We also compared digital photomicrographs with whole-slide images (WSI) as material for ImmunoMembrane DIA. We stained 750 surgical resection specimens of invasive breast cancers immunohistochemically for HER2 and analysed staining with ImmunoMembrane. The ImmunoMembrane DIA scores were compared with the originally responsible pathologists' visual scores, a researcher's visual scores and in situ hybridisation (ISH) results. The originally responsible pathologists reported 9.1 % positive 3+ IHC scores, for the researcher this was 8.4 % and for ImmunoMembrane 9.5 %. Equivocal 2+ scores were 34 % for the pathologists, 43.7 % for the researcher and 10.1 % for ImmunoMembrane. Negative 0/1+ scores were 57.6 % for the pathologists, 46.8 % for the researcher and 80.8 % for ImmunoMembrane. There were six false positive cases, which were classified as 3+ by ImmunoMembrane and negative by ISH. Six cases were false negative defined as 0/1+ by IHC and positive by ISH. ImmunoMembrane DIA using digital photomicrographs and WSI showed almost perfect agreement. In conclusion, digital image analysis by ImmunoMembrane can help to resolve a majority of equivocal 2+ cases in HER2 IHC, which reduces the need for ISH testing.
BioMediTech/Cancer Biology, University of Tampere, 33014, Tampere, Finland.
Henrik O
HO
Helin
BioMediTech/Cancer Biology, University of Tampere, 33014, Tampere, Finland.
Vilppu J
VJ
Tuominen
BioMediTech/Cancer Biology, University of Tampere, 33014, Tampere, Finland.
Onni
O
Ylinen
HUSLAB, Division of Pathology and Genetics, Helsinki University Central Hospital, P.O. Box 400, 00029 HUS, Finland.
Heikki J
HJ
Helin
BioMediTech/Cancer Biology, University of Tampere, 33014, Tampere, Finland. jorma.isola@uta.fi.
Jorma
J
Isola
D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D015588:Observer Variation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D015203:Reproducibility of Results; D012984:Software; D046888:Tissue Array Analysis / Q000379:methods
D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
Breast cancer; Computer-assisted image analysis; Digital pathology; HER2; Immunohistochemistry; Whole-slide imaging