Histopathological prostate cancer characteristics at radical prostatectomy after population based screening

Abstract

Purpose: Although early detection of prostate cancer by prostate specific antigen based screening results in a shift towards more clinically organ confined tumors, changes in prostate cancer characteristics after radical prostatectomy are less clear.

Materials and methods: We studied 121 totally embedded radical prostatectomy specimens that were obtained from consecutive participants of the European Randomized Study of Screening for Prostate Cancer who were systematically screened and treated surgically. In each specimen pathological stage, Gleason score and proportion of high grade cancer (Gleason pattern 4 or 5) were determined. Lymph node status at operation, stage and grade were compared to a historical series of 72 surgical procedures performed for clinically localized prostate cancer at our hospital before the introduction of serum prostate specific antigen as a diagnostic tool.

Results: Although none of the screen detected cases had positive lymph nodes at surgery, operation was discontinued in 13 (18%) of the 72 historical cases because of positive lymph nodes. Compared with the remaining 59 historical prostatectomy specimens, the screen detected specimens showed a definite increase in the frequency of pathologically organ confined tumors and a relative decrease in Gleason score 8 to 10 tumors. However, 60% of screen detected tumors contained areas with high grade cancer (Gleason pattern 4 or 5) and 50% had a Gleason score of 7. The relative amount of high grade cancer in each tumor was related to volume (Kruskal-Wallis test p <0. 001).

Conclusions: Screening for prostate cancer leads to an increase in surgical treatment for relatively small tumors that have a higher probability of being organ confined. Although the frequency of positive lymph nodes at operation decreases dramatically and the proportion of organ confined tumors after surgery increases, there is a shift from Gleason 8 to 10 tumors towards lower grade tumors at radical prostatectomy. Still, judged by the high frequency of focal dedifferentiation in screen detected tumors, most of them and surgically treated tumors are likely to be clinically important. The relatively large accumulation of these tumors in the Gleason 7 category is a concern because it could lead to a decrease in the clinical usefulness of the Gleason score system.