TY - GEN
T1 - An inter-observer Ki67 reproducibility study applying two different assessment methods
T2 - 16th Acta Oncologica Symposium
AU - Laenkholm, Anne-Vibeke
AU - Grabau, Dorthe
AU - Møller Talman, Maj-Lis
AU - Balslev, Eva
AU - Bak Jylling, Anne Marie
AU - Tabor, Tomasz Piotr
AU - Johansen, Morten
AU - Brügmann, Anja
AU - Lelkaitis, Giedrius
AU - Di Caterino, Tina
AU - Mygind, Henrik
AU - Poulsen, Thomas
AU - Mertz, Henrik
AU - Søndergaard, Gorm
AU - Bruun Rasmussen, Birgitte
PY - 2018/1/2
Y1 - 2018/1/2
N2 - INTRODUCTION: In 2011, the St. Gallen Consensus Conference introduced the use of pathology to define the intrinsic breast cancer subtypes by application of immunohistochemical (IHC) surrogate markers ER, PR, HER2 and Ki67 with a specified Ki67 cutoff (>14%) for luminal B-like definition. Reports concerning impaired reproducibility of Ki67 estimation and threshold inconsistency led to the initiation of this quality assurance study (2013-2015). The aim of the study was to investigate inter-observer variation for Ki67 estimation in malignant breast tumors by two different quantification methods (assessment method and count method) including measure of agreement between methods.MATERIAL AND METHODS: Fourteen experienced breast pathologists from 12 pathology departments evaluated 118 slides from a consecutive series of malignant breast tumors. The staining interpretation was performed according to both the Danish and Swedish guidelines. Reproducibility was quantified by intra-class correlation coefficient (ICC) and Lights Kappa with dichotomization of observations at the larger than (>) 20% threshold. The agreement between observations by the two quantification methods was evaluated by Bland-Altman plot.RESULTS: For the fourteen raters the median ranged from 20% to 40% by the assessment method and from 22.5% to 36.5% by the count method. Light's Kappa was 0.664 for observation by the assessment method and 0.649 by the count method. The ICC was 0.82 (95% CI: 0.77-0.86) by the assessment method vs. 0.84 (95% CI: 0.80-0.87) by the count method.CONCLUSION: Although the study in general showed a moderate to good inter-observer agreement according to both ICC and Lights Kappa, still major discrepancies were identified in especially the mid-range of observations. Consequently, for now Ki67 estimation is not implemented in the DBCG treatment algorithm.
AB - INTRODUCTION: In 2011, the St. Gallen Consensus Conference introduced the use of pathology to define the intrinsic breast cancer subtypes by application of immunohistochemical (IHC) surrogate markers ER, PR, HER2 and Ki67 with a specified Ki67 cutoff (>14%) for luminal B-like definition. Reports concerning impaired reproducibility of Ki67 estimation and threshold inconsistency led to the initiation of this quality assurance study (2013-2015). The aim of the study was to investigate inter-observer variation for Ki67 estimation in malignant breast tumors by two different quantification methods (assessment method and count method) including measure of agreement between methods.MATERIAL AND METHODS: Fourteen experienced breast pathologists from 12 pathology departments evaluated 118 slides from a consecutive series of malignant breast tumors. The staining interpretation was performed according to both the Danish and Swedish guidelines. Reproducibility was quantified by intra-class correlation coefficient (ICC) and Lights Kappa with dichotomization of observations at the larger than (>) 20% threshold. The agreement between observations by the two quantification methods was evaluated by Bland-Altman plot.RESULTS: For the fourteen raters the median ranged from 20% to 40% by the assessment method and from 22.5% to 36.5% by the count method. Light's Kappa was 0.664 for observation by the assessment method and 0.649 by the count method. The ICC was 0.82 (95% CI: 0.77-0.86) by the assessment method vs. 0.84 (95% CI: 0.80-0.87) by the count method.CONCLUSION: Although the study in general showed a moderate to good inter-observer agreement according to both ICC and Lights Kappa, still major discrepancies were identified in especially the mid-range of observations. Consequently, for now Ki67 estimation is not implemented in the DBCG treatment algorithm.
KW - Biomarkers/metabolism
KW - Breast Neoplasms/pathology
KW - Consensus Development Conferences as Topic
KW - Denmark
KW - Female
KW - Humans
KW - Immunohistochemistry/standards
KW - Ki-67 Antigen/metabolism
KW - Pathology, Clinical/standards
KW - Practice Guidelines as Topic
KW - Reproducibility of Results
KW - Staining and Labeling/methods
UR - http://www.scopus.com/inward/record.url?scp=85036652547&partnerID=8YFLogxK
U2 - 10.1080/0284186X.2017.1404127
DO - 10.1080/0284186X.2017.1404127
M3 - Conference article in Journal
C2 - 29202622
SN - 0284-186X
VL - 57
SP - 83
EP - 89
JO - Acta Oncologica
JF - Acta Oncologica
IS - 1
M1 - 1404127
Y2 - 18 January 2018 through 19 January 2018
ER -