Ki67 is a nuclear protein expressed throughout the energetic phases of the cell cycle, which makes it a biomarker of cell proliferation. In medical pathology settings, immunohistochemical (IHC) detection of Ki67 is used to calculate Ki67 proliferation indices (PIs), which have prognostic info and are used to subdivide breast carcinomas and neuroendocrine neoplasias. Calculation of Ki67 PIs is notoriously arduous and vulnerable to intraobserver and interobserver variance.
As well as, IHC protocol settings [such as primary antibody (Ab) clone, clone format, and stainer platform] can have an effect on the results of the IHC assays and in flip the Ki67 PI. Digital picture evaluation has been prompt as a great tool to standardize Ki67 counting. Just lately, digital double staining, a pc algorithm segmenting Ki67 and Ki67 tumor cells utilizing digitally fused parallel cytokeratin and Ki67-stained slides, has been launched.
On this examine, we evaluate Ki67 PIs obtained by digital double staining in 41 breast carcinomas stained utilizing probably the most generally used commercially accessible major Ab clones and codecs on the principle stainer platforms. IHC protocols for the concentrated (conc) Ab and platform mixtures had been optimized for the very best analytical sensitivity and optimum signal-to-noise ratio, whereas ready-to-use (RTU) codecs had been used, as beneficial by the seller.
Vital variations within the imply Ki67 PIs (relativized to the imply core Ki67) had been noticed not solely between the totally different Ab clones but in addition the totally different codecs and stainer platforms; Ki67 PIs with SP6 conc stained on the Ventana BenchMark ULTRA platform had been on common 11.9 proportion factors (pp) larger than the imply core common, whereas with Ab 30.9 RTU on the Ventana platform, they had been 10.
Four pp larger. Mib1 RTU (Dako Autostainer Hyperlink 48) and MM1 RTU (Leica Bond) supplied 8.6 and 12.5 pp decrease Ki67 PIs, respectively. Mib1 conc and SP6 conc on the Dako Autostainer and Leica Bond supplied comparable results-close to the general common. Vital variations within the proportion of tumors with Ki67 high-level expression (Ki67 PI ≥20%) had been noticed amongst Ab, format, and stainer platform mixtures.
The outcomes underline the challenges within the comparability of Ki67 PIs throughout Abs, codecs, and platforms. Researchers and clinicians have to account for these variations when reporting Ki67 PIs. To advance the usefulness of Ki67 PIs within the analysis and medical setting, standardization of Ki67 IHC assays is required.