Histopathologic diagnosis and classification of prostate adenocarcinoma: biologic significance.

Early diagnosis and accurate, biologically meaningful classification of prostate neoplasia remain important goals. The relation of evolving clinicopathologic concepts of histologic appearances to potential tumor progression is a major advance in classification of prostatic neoplasia. The criteria for recognizing incidental or "occult" stage A-l adenocarcinomas remain problematic in diagnosis, and focal neoplasms with little or no propensity to progression must be differentiated from cancers with a high likelihood of aggressive behavior. Current histologic grading systems in classifying prostate adenocarcinoma accurately identify two cancer subsets: 1) focal well differentiated tumors which rarely progress, and 2) diffuse poorly differentiated tumors which invariably develop metastatic disease. Unfortunately, the majority of prostatic cancers are classified in the intermediate group in which the prognosis is variable and difficult to differentiate purely by histology. Our laboratory recently adapted image analysis of cellular DNA quantitation--a major improvement in accurately predicting tumor behavior, especially in the intermediate histologic grades. We and others have found that tumors with abnormal (aneuploid) DNA content are more likely to progress than neoplasms with normal (diploid) DNA content.