Serum Prostate Specific Antigen. Clinical Assessment as a Tumor Marker for the Prostate Cancer

Ha, Dal Bong; Kim, Chun Il; Lee, Sung Choon

Abstract

We evaluated a clinical usefulness of prostate specific antigen (PSA) as a tumor marker for prostate cancer. Serum PSA values were obtained from 32 patients with prostatic adenocarcinoma(group I ),81 with histologically diagnosed BPH(group II ) and 147 with clinically diagnosed BPH(group III). Mean PSA values were 121.5, 9.3 and 3.6ng/ml, respectively. To enhance the accuracy of serum PSA, we have used the quotient of serum PSA and prostatic volume, PSA density. In group I, 31 patients(97%) had PSA values over 10ng/ml and PSA density over 0.15. In group II, 27 patients(33%) had PSA values over 10ng/ml and 35(43%) had PSA density over 0.15. The PSA values of extraprostatic cancer were higher than that of organ-confined cancer in group I (p<0.05). Among 3 groups divided by combined Gleason score, low 2-4, intermediate 5-7 and high 8-l0, statistically significant differences were not noticed in PSA values (p > 0.05). Of 18 patients with stage D2 prostate cancer treated with orchiectomy, 11 had PSA values decreased to normal range within 6 months. Serum PSA values of 2 patients who have clinically progressive disease were increased after 6 months. In 3 of 4 patients treated with radiotherapy during follow-up of 18 months, post irradiation PSA values were 2.4, 5.6 and 11.2ng/ml, respectively. Only 1 patient who have a positive bone scan had an elevated PSA value of more than 100ng/ml. We suggest that serum PSA is not a excellent marker on screening test for prostate cancer because of a high false positive rate. However, PSA is useful for following disease progression, response to therapy and determining indication of bone scan.