A topical update on free/total PSA

Two recent publications have dealt with issues related to the appropriate application of the free/total PSA ratio test in patients at potential risk for prostate cancer.

Dirim et al. assessed total serum PSA and free/total (f/t) serum PSA changes after antibiotic treatment in 85 patients with a normal DRE but elevated age-adjusted total serum PSA levels in comparison to the patients’ biopsy results. The results of this study showed that:

  • Serum PSA levels decreased after antibiotic treatment in 47/85 patients.
  • The f/t PSA ratio decreased or remained unchanged in 21 and increased in 26 of these 47 cases.
  • The prostate cancer detection rate in the former group was 52.4 percent (11/21) on biopsy, while it was 7.7 percent (2/26) in the latter group (p = 0.002).
  • There were 38 patients with increased PSA levels after antibiotics.
  • The f/t PSA ratios decreased or remained unchanged in 20 and increased in 18 of these 38 cases.
  • Cancer detection rates were 55 percent (11/20) in the former and 16.7 percent (3/18) in the latter group (p = 0.003).

Dirim and colleagues conclude that PSA and f/t PSA levels may change with long-term antibiotic treatment in patients with elevated PSA values. However, the f/t PSA ratio rather than the total PSA level appears to be more helpful in suggesting risk for prostate cancer in such patients.

In the second study, Yokomizo et al. compared the results of 12- and 8-core biopsies in 419 patients with PSA levels of 4.0-20.0 ng/ml and examined whether the f/t PSA ratio is useful for cancer detection in 12-core biopsy.

The results of this study can be summarized as follows:

  • 235 men underwent 8-core biopsy and 184 underwent 12-core biopsy.
  • The cancer detection rate in the 12-core group (35.9 percent) was significantly higher than in the 8-core group (23.8 percent).
  • When the f/t PSA ratio was < 0.11, the cancer detection rate was 53.1 percent in the 12-core biopsy group.

This study would seem to suggest that an f/t PSA ratio of < 0.11 can be indicative of a greater probability of prostate cancer prior to biopsy in men with a total PSA level of between 4 and 20 ng/ml — so long as a 12-core biopsy is being used. It should be noted that the 12-core biopsy has pretty much become the accepted standard for initial biopsies in US patients at risk for prostate cancer.

2 Responses

  1. A tale of 2 PSA results:

    May 2009 — Free PSA 49.6; total PSA 11.7

    Oct 2009 — Free PSA 0.14; total PSA 1.96

    Medications: Avodart and Flomax

    Any comments on this?


  2. So in May your f/t PSA ratio was 4.2 and in October it was 0.07. You had been treated with a standard form of treatment for benign prostatic hyperplasia, and you appear to have responded in an appropriate manner.

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