[Advanced prostate cancer with normal serum prostate-specific antigen values]

Although prostate-specific antigen (PSA) is a valuable marker of prostate cancer, some untreated patients with advanced prostate cancer have normal PSA values. Over a period of 5 years, we reviewed pretreatment serum PSA levels in 131 patients with advanced prostate cancer (stages C and D). Ten patients (7.6%) had normal PSA values. The histological type of prostate cancer associated with normal PSA values was variable and the prognosis was not so poor. Immunostaining for PSA was performed on the resected prostate tissue of the 10 patients. PSA staining was positive in 5 cases, negative in 3 cases, and equivocal in the remaining 2 cases. In conclusion, PSA is not always useful, especially for following patients with normal PSA values.