[A study on parameters to predict tumor volume for stage T1c prostate cancers of Gleason score 6 or less]

The number of cases of stage T1c prostate cancer has dramatically been increasing since the introduction of PSA as a screening test. The patients with T1c prostate cancer are usually treated by radical prostatectomy. In this group, however, some cancers are of small tumor volume and with a Gleason score of less than 7. These cancers are considered to be good candidates for watchful waiting management. We have investigated 40 patients with T1c prostate cancer treated by radical prostatectomy between 1996 and 1998. All 9 patients harboring tumors of Gleason score 7 or greater had tumors larger than 0.5 cm3. We have investigated PSA-related parameters including total PSA (PSA), PSA density (PSAD), free PSA, and % free PSA in 31 patients with T1c cancers of Gleason score 6 or less in order to clarify good preoperative predictors of tumor volume. We compared the distribution of PSA, PSAD, free PSA, and % PSA between the larger and smaller tumor groups. There was no significant difference in PSA, PSAD, or free PSA value. The small tumor group had a greater mean % free PSA than the larger tumor group (23.27 versus 11.88, p = 0.007). Areas under receiver operating characteristic curves were 0.715, 0.794, 0.636, and 0.842 for PSA, PSAD, free PSA and % free PSA. In stage T1c prostate cancer of Gleason score 6 or less, % free PSA may be the most useful preoperative predictor for tumor volume of 0.5 cm3 or greater.