 The fraction of Ki-67-positive tumor cells (the "Ki-67 labeling index") is often correlated with the clinical course of cancer.The best-studied examples in this context are prostate, brain and breast carcinomas, as well as nephroblastoma and neuroendocrine tumors.For these types of tumors, the prognostic value for survival and tumor recurrence have repeatedly been proven in uni- and multivariate analysis.