Prostate-specific antigen, Gleason sum and clinical T stage for predicting the need for radionuclide bone scan for prostate cancer patients in Japan

Aim: In the present study, we evaluated the relationships between prostate-specific antigen (PSA) level and bone metastasis, between Gleason sum and bone metastasis, and between clinical T stage and bone metastasis in Japanese patients. Methods: Between November 1998 and June 2004, we performed ultrasound-guided biopsies on 709 patients (mean age: 70.5 years, range: 39-90). Prostate cancer was detected in 339 patients (47.8%), 297 (87.6%) of whom underwent a radionuclide bone scan. In close collaboration with orthopedists, bone computed tomography scans, bone magnetic resonance imaging and/or plain rentogenograms were performed for cases that were difficult to diagnose as bone metastasis through radionuclide bone scans only. Results: We detected 61 (20.6%) bone metastasis cases in 296 patients. A simple linear regression analysis between log[PSA] and bone metastasis (n = 296) produced a significant relationship (P < 0.05). When we set the cut-off PSA value for the indication for a bone scan at 15 ng/mL, the possibility of bone metastasis was 10%. However, from our experience, there was no bone metastasis in the patients whose Gleason sums were less than five, and in the patients whose Gleason sum were five or more, and the PSA levels were less than 15, there was no bone metastasis. The rate of bone metastasis increased with the increase of PSA level. In the clinical T-1-T-2 stage cases, there were significant higher PSA levels in the cases with bone metastasis. In the T-1-T-2 patients whose PSA levels were less than 16, there was no bone metastasis. Conclusions: From the analysis of PSA, Gleason sum and clinical T stage, we suggest that bone scan is unnecessary for patients whose PSA level is less than 15 ng/mL or Gleason sum is less than five.