Systematic association of PAP and PSA determinations to bone scintigraphy in prostatic cancer.

Prostate-specific antigen (PSA) was compared to prostatic acid phosphatase (PAP) in patients with prostatic cancer suspected to have bone metastases. Bone scans were classified according to metastatic skeletal involvement. The sensitivity of PSA in predicting the presence of metastatic disease (68%) was better than that of PAP (53%). Specificity was 79% for PSA and 90% for PAP. Thirty-five patients had a positive PSA level and a normal scintigraphy (false-positive); 14 of them had only endoscopic prostate resection. Thirty-eight patients underwent a further exploration 3-18 months later. PSA level during disease was correlated to scintigraphy in 32 of 38 patients.