DNA-grading of prostatic carcinoma: prognostic validity and reproducibility.

The prognostic significance of the DNA-Malignancy-Grade (DNA-MG) was tested in 52 prostatic carcinoma patients in comparison with a cytomorphological grading system and the clinical staging. Papanicolaou- or MGG stained smears from transrectal aspiration biopsies were automatically restained according to Feulgen in a modified Shandon staining machine. The DNA-MG, based on the variation of the nuclear DNA content of tumor cells around the normal DNA peak, ranges on a continuous scale from 0.01 to 3.0. It was determined with a TV-image analysis system (Leitz, TAS plus), combined with an automatic microscope. The DNA-MG revealed a high prognostic validity, the clinical stage showed only a minor influence on the survival time and the cytopathologic grading system was of insufficient prognostic information. Significant differences in survival time could be demonstrated between patients with DNA-MGs of 0.01-1.5 and 1.5-3.0, as well as with DNA-MGs 1.0-2.0 and 2.0-3.0. The intra- and interobserver variations of the DNA grading system were found to be sigma = 0.014 and sigma = 0.036 respectively. The reproducibilities were 86.7% for intra- and interobserver measurements, when the continuous DNA-MG scale was divided in three groups.