Interactive cytometry, chance or evil of bias?

Interactive selection of a limited number of cells in imaging cytometry for determining the DNA histogram of breast cancer cells as the best known prognosticator at the moment, implies statistical and systematic sampling problems. Analysis of histograms of 361 breast cancer aspirate specimens measured in two laboratories demonstrate the expected high statistical variations in view of the only 100 cells measured per case but also slight systematic differences. Controlled systematic sampling without pathological bias results in a somewhat higher malignancy grading than selective biased sampling. For this finding we have no explanation. The main result is, however, that we did not find the expected contrary which makes the argument for at least this application invalid that expert pathologists are needed for reliable interactive sampling.