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[Molecular forms of PSA and differentiating between benign hypertrophy,carcinoma, and disseminated prostatic
C Sáez Lavilla1, A Guallar Labrador, J Castrillo Rubio
1Servicio de Medicina Nuclear, Hospital Miguel Servet, Zaragoza, España.
Objective:
To determine the correlation between two methods of measurement of total PSA (PSA-T) and free PSA (PSA-F) and the utility of the PSA-F/PSA-T ratio in patients with PSA-T between 4 and 10 ng/ml suspected as having prostate cancer.
Methods:
Determinations of both PSA-T and PSA-F were performed using two different techniques in 91 patients suspected as having prostate cancer. Diagnosis was made on the findings of biopsy and the complementary tests.
Results:
The following correlation was found for the two techniques: R = 0.99 and p < 0.05 for PSA-T, and R = 0.85 and p < 0.05 for PSA-F. For PSA-T values of 4-10 ng/ml and PSA-F greater than 25%, we found two patients with prostate cancer. For a PSA-F/PSA-T ratio less than 9%, all cases had prostate cancer. Three cases with bone metastasis had PSA-T values less than 10 ng/ml.
Conclusions:
A PSA-F/PSA-T ratio greater than 25% does not exclude malignancy in patients with a total PSA of 4-10 ng/ml; values less than 9% correspond to prostate cancer. Bone metastasis was found with both methods in patients with total PSA values less than 10 ng/ml.