Biochemical outcome of small-volume or insignificant prostate cancer treated with radical prostatectomy in Japanese population.

BACKGROUND

We investigated the biochemical outcome of small-volume prostate cancers [tumor volume (TV) < 0.5 mL, SVCa] and insignificant prostate cancers (TV <0.5 mL without any Gleason pattern 4/5 elements, InsigCa) treated with radical prostatectomy.

METHODS

Between April 2000 and May 2010, 609 patients with prostate cancer underwent radical prostatectomy at Hirosaki University Graduate School of Medicine. Of these, 237 were excluded from the study because of preoperative adjuvant therapy. The remaining 372 patients underwent routine histopathological and TV evaluations. Biochemical recurrence (BCR) was defined as the presence of prostate-specific antigen (PSA) levels greater than 0.2 ng/mL after prostatectomy.

RESULTS

The median patient age was 68 years (range 48-78 years) and the median preoperative PSA level was 7.50 ng/mL. The mean follow-up period was 45.9 months and the mean TV was 2.16 mL. Sixty patients (16.3%) had SVCa and 14 (3.7%) had InsigCa. The 5-year BCR-free survival rate for patients with SVCa was 67.3% and that for patients with a TV of 0.5 or greater was 87.1%. A significant difference was seen between the groups using the log-rank test (P = 0.008). We could not identify any BCR in patients with InsigCa.

CONCLUSION

Despite the limited number of cases, patients with InsigCa did not develop BCR whereas 12.9% of those with SVCa developed BCR after radical prostatectomy within 5 years. Accurate prediction of the biochemical outcome of SVCa remains difficult and further studies are needed.