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Assessment of Ki67 expression for breast cancer subtype classification and prognosis in the Nurses' Health Study.

ABSTRACT: PURPOSE:Ki67 is a proliferation marker commonly assessed by immunohistochemistry in breast cancer, and it has been proposed as a clinical marker for subtype classification, prognosis, and prediction of therapeutic response. However, the clinical utility of Ki67 is limited by the lack of consensus on the optimal cut point for each application. METHODS:We assessed Ki67 by immunohistochemistry using Definiens digital image analysis (DIA) in 2653 cases of incident invasive breast cancer diagnosed in the Nurses' Health Study from 1976 to 2006. Ki67 was scored as continuous percentage of positive tumor cells, and dichotomized at various cut points. Multivariable hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox regression models for distant recurrence, breast cancer-specific mortality and overall mortality in relation to luminal subtypes defined with various Ki67 cut points, adjusting for breast cancer prognostic factors, clinico-pathologic features and treatment. RESULTS:DIA was highly correlated with manual scoring of Ki67 (Spearman correlation ? = 0.86). Mean Ki67 score was higher in grade-defined luminal B (12.6%), HER2-enriched (17.9%) and basal-like (20.6%) subtypes compared to luminal A (8.9%). In multivariable-adjusted models, luminal B tumors had higher breast cancer-specific mortality compared to luminal A cancer classified using various cut points for Ki67 positivity including the 14% cut point routinely reported in the literature (HR 1.38, 95% CI 1.11-1.72, p = 0.004). There was no significant difference in clinical outcomes for ER- tumors according to Ki67 positivity defined at various cut points. CONCLUSIONS:Assessment of Ki67 in breast tumors by DIA was a robust and quantitative method. Results from this large prospective cohort study provide support for the clinical relevance of using Ki67 at the 14% cut point for luminal subtype classification and breast cancer prognosis.

SUBMITTER: Healey MA

PROVIDER: S-EPMC6995281 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Assessment of Ki67 expression for breast cancer subtype classification and prognosis in the Nurses' Health Study.

Healey Megan A MA Hirko Kelly A KA Beck Andrew H AH Collins Laura C LC Schnitt Stuart J SJ Eliassen A Heather AH Holmes Michelle D MD Tamimi Rulla M RM Hazra Aditi A

Breast cancer research and treatment 20170808 2

<h4>Purpose</h4>Ki67 is a proliferation marker commonly assessed by immunohistochemistry in breast cancer, and it has been proposed as a clinical marker for subtype classification, prognosis, and prediction of therapeutic response. However, the clinical utility of Ki67 is limited by the lack of consensus on the optimal cut point for each application.<h4>Methods</h4>We assessed Ki67 by immunohistochemistry using Definiens digital image analysis (DIA) in 2653 cases of incident invasive breast canc ...[more]

PMID: 28791482

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Project description:BackgroundAs a marker for tumor cell proliferation, Ki67 has important impacts on breast cancer (BC) prognosis. Although immunohistochemical staining is the current standard method, variations in analytical practice make it difficult for pathologists to manually measure Ki67 index. This study was to develop a fluorescent spectrum-based quantitative analysis of Ki67 expression by quantum-dots (QDs) multiple imaging technique.MethodsA QDs-based in situ multiple fluorescent imaging method was developed, which stained nuclear Ki67 as red signal and cytoplasmic cytokeratin (CK) as green signal. Both Ki67 and CK signals were automatically separated and quantified by professional spectrum analysis software. This technique was applied to tissue microarrays from 240 BC patients. Both Ki67 and CK values, and Ki67/CK ratio were obtained for each patient, and their prognostic value on 5-year disease free survival was assessed.ResultsThis method simultaneously stains nuclear Ki67 and cytoplasmic CK with clear signal contrast, making it easy for signal separation and quantification. The total fluorescent signal intensities of both Ki67 sum and CK sum were obtained, and Ki67/CK ratio calculated. Ki67 sum and Ki67/CK ratio were each attributed into two grades by X-tile software based on the best P value principle. Multivariate analysis showed Ki67 grade (P = 0.047) and Ki67/CK grade (P = 0.004) were independent prognostic factors. Furthermore, area under curve (AUC) of ROC analysis for Ki67/CK grade (AUC: 0.683, 95%CI: 0.613-0.752) was higher than Ki67 grade (AUC: 0.665, 95%CI: 0.596-0.734) and HER-2 gene (AUC: 0.586, 95%CI: 0.510-0.661), but lower than N stage (AUC: 0.760, 95%CI: 0.696-0.823) and histological grade (AUC: 0.756, 95%CI: 0.692-0.820) on predicting the risk for recurrence.ConclusionsA QDs-based quantitative and in situ multiple imaging on Ki67 and CK was developed to improve Ki67 assessment in BC, and Ki67/CK grade had better performance than Ki67 grade in predicting prognosis.

Dataset Information

Assessment of Ki67 expression for breast cancer subtype classification and prognosis in the Nurses' Health Study.

Publications

Assessment of Ki67 expression for breast cancer subtype classification and prognosis in the Nurses' Health Study.

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