[Incidental prostate cancer: volume, location and degree of differentiation of the tumor in the radical prostatectomy specimen and value of subclassification to stage A1 and A2].

Morphometric analysis was performed on 22 radical prostatectomy specimens of clinical stage A1 and 22 specimens of stage A2 prostate cancers. Of 44 stage A cancers (86%), 38 arose in the transition zone of the prostate, while only 6 were peripheral zone tumors. The subclassification into stages A1 and A2 based on the percentage of cancer in the transurethral resection specimen was not able reliably to separate patients with high-volume stage A cancer from those with low-volume stage A cancer. The same was true when the patients were subclassified according to the criteria of the TNM system (TNM 1987). However, all cases (n = 6) with Gleason grade 4 elements in the TUR chips had relatively high-volume residual TUR cancer (greater than or equal to 1.7 cm3) in the radical specimen. Unsuspected cancers unrelated to the incidental prostate cancer were found in 73% of the specimens. The vast majority (87%) were peripheral zone cancers. Eight unsuspected cancers were larger than the Stage A cancer, but only 2 of the 8 were larger than 1 cm3. Our data suggest that the subclassification of stage A into stages A1 and A2 or the subclassification according to the TNM criteria (TNM 1987) does not reliably separate patients who are at risk of cancer progression. Further diagnostic procedures are necessary in these patients. Post-TUR serum PSA levels (Yang) provided valuable additional information in this series. Post-TUR PSA levels increased with increasing residual cancer volume in the prostate. Below a post-TUR PSA of 1 ng/ml, total residual cancer volume was less than 0.4 cm3 in 7 of 8 cases.(ABSTRACT TRUNCATED AT 250 WORDS)