Prostatic intraepithelial neoplasia (PIN) is regarded as the most important premalignant lesion of prostatic epithelium. The aim of this investigation was to find clues to formal pathogenesis of
prostatic cancer. For this purpose
DNA ploidy (determined by means of image cytometry [ICM] using 4-microns-thick Feulgen-stained
paraffin sections) of PIN and invasive
carcinoma was compared. Prostatic tissue of 72 patients (mean age, 67.5 years; 82 areas with
carcinoma and 71 areas with PIN) was examined. In 44 cases PIN and
carcinoma were coexistent in the same prostates, the PIN grade being high in 77% of these cases (P < .05). In higher-grade PIN and higher-grade
carcinoma the c-values, 2.5c-exceeding-rate, and
aneuploidy rate increased (P < .01).
Carcinomas associated with diploid PIN (either low or high grade) showed diploidy and
aneuploidy in an equal number of cases, whereas 70% of
aneuploid PIN cases (all high grade) were associated with
aneuploid invasive
carcinomas (P < .01). Conversely, in 71% of the cases with
aneuploid carcinoma the coexistent PIN (either low or high grade) was diploid. Our findings show that
aneuploidy can be acquired at a preinvasive stage of
carcinogenesis in the prostate and suggest that
aneuploid high-grade PIN might be regarded as a precursor of some but not all
aneuploid prostatic
carcinomas. Image cytometry analysis seems to be a promising method for further subclassification of high-grade PIN lesions into groups with putatively lower or higher risk. However, further investigation is necessary to confirm the clinical importance of these results.