The Free-to-Total Prostate-Specific Antigen (PSA) Ratio in Chinese Patients Who Underwent Transurethral Resection of the Prostate

OBJECTIVE: To elucidate the change of the free-to-total prostate-specific antigen (PSA) ratio in ethnic Chinese who have undergone transurethral resection of the prostate (TURP). MATERIALS AND METHODS: Serum total PSA and free PSA were determined before and 6 months or later after TURP in 92 patients who underwent TURP under the impression of benign prostatic hyperplasia (BPH). Patients were divided to 2 groups: group A (n=41) were patients whose total PSA was less than 4 ng/ml, while that of group B (n=51) was greater than or equal to 4 ng/ml. Changes in serum total PSA, free PSA, as well as the free-to-total (F/T) PSA ratio were compared preoperatively and postoperatively. Moreover, changes in serum total PSA, free PSA, the F/T PSA ratio, the uroflow rate, and prostatic weight between groups A and B were evaluated. RESULTS: In group A patients, the serum total PSA and free PSA were significantly reduced from 2.38±1.04 and 0.81±0.48 ng/ml preoperatively to 0.98±0.67 and 0.31±0.16 ng/ml postoperatively (p＜0.001, respectively), but the F/T PSA ratio remained relatively consistent after TURP (0.35±0.14 vs. 0.38±0.17, p=0.364). In group B patients, the serum total PSA and free PSA were also significantly reduced from 9.14±6.15 and 2.53±1.69 ng/ml preoperatively to 3.71±5.24 and 0.75±0.46 ng/ml postoperatively (p＜0.001, respectively); however the F/T ratio remained consistent after TURP (0.28±0.05 vs. 0.31±0.31,p=0.478). Moreover between group A and B patients, preoperatively or postoperatively significant differences in total PSA and free PSA were also revealed, while the F/T PSA ratio remained relatively consistent (0.35±0.14 vs. 0.28±0.05, p=0.01,preoperatively; 0.38±0.17 vs. 0.31±0.31, p=0.236, postoperatively). The prostatic weight changed from 26.14±8.14g preoperatively to 13.90±3.53 g postoperatively (p＜0.001) in group A patients, and 43.79±25.49 g to 21.17±10.40 g (p＜0.001) in group B patients. Two B group patients subsequently developed prostatic cancer. Their follow-up total PSA (11.30 and 3.55 ng/ml, respectively) and free PSA (0.95 and 0.32 ng/ml, respectively) were variable, and their F/T PSA ratios were low (0.08 and 0.09, respectively). In contrast to the relatively consistent F/T PSA ratios in the pre-TURP (0.27 and 0.26, respectively) and post-TURP status (0.30 and 0.28, respectively), changes in the follow-up F/T PSA ratios in these 2 patients were remarkable (0.08 and 0.09, respectively). CONCLUSIONS：While serum total PSA and free PSA were significantly reduced after TURP, the free-to-total PSA ratio remained consistent before and after TURP, both in patients with normal PSA and in patients with high PSA. The same clinical vigilance for prostate cancer in men who undergo TURP should be maintained. A decrease in the F/T PSA ratio may be used to alert physicians for the earlier detection of malignancy.