Prognostic value of Ki-67 for prostate cancer death in a conservatively managed cohort
A partir de l'analyse immunohistochimique de biopsies prélevées à l'aiguille sur 293 patients atteints d'un cancer localisé de la prostate, cette étude évalue, par rapport à une analyse histopathologique des échantillons de résection, l'intérêt d'un indice basé sur l'expression tumorale de l'antigène Ki-67 pour prédire le risque de décès associé à la maladie
Background : Standard clinical parameters cannot accurately differentiate indolent from aggressive prostate cancer. Our previous work showed that immunohistochemical (IHC) Ki-67 improved prediction of prostate cancer death in a cohort of conservatively treated clinically localised prostate cancers diagnosed by transurethral resection of the prostate (TURP). Here, we present results in a more clinically relevant needle biopsy cohort.
Methods : Biopsy specimens were microarrayed. The percentage of Ki-67 positively stained malignant cells per core was measured and the maximum score per individual used in analysis of time to death from prostate cancer using a Cox proportional hazards model.
Results : In univariate analysis (n=293), the hazard ratio (HR) (95% confidence intervals) for dichotomous Ki-67 (less than or equal to10%, >10%) was 3.42 (1.76, 6.62)
χ2 (1 df)=9.8, P=0.002. In multivariate analysis, Ki-67 added significant predictive information to that provided by Gleason score and prostate-specific antigen (HR=2.78 (1.42, 5.46), χ2 (1 df)=7.0, P=0.008).
Conclusion
:The IHC Ki-67 scoring on prostate needle biopsies is practicable and yielded significant prognostic information. It was less informative than in the previous TURP cohort where tumour samples were larger and more comprehensive, but in more contemporary cohorts with larger numbers of biopsies per patient, Ki-67 may prove a more powerful biomarker.
British Journal of Cancer , résumé, 2012