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The ratio of free to total serum prostate specific antigen and its use in differential diagnosis of prostate carcinoma in japan

  1. Shin Egawa M.D.1,*,
  2. Shigehiro Soh M.D.1,
  3. Makoto Ohori M.D.1,
  4. Toyoaki Uchida M.D.1,
  5. Kazuo Gohji M.D.2,
  6. Akio Fujii M.D.2,
  7. Sadahito Kuwao M.D.3,
  8. Ken Koshiba M.D.1

Article first published online: 27 SEP 2000

DOI: 10.1002/(SICI)1097-0142(19970101)79:1<90::AID-CNCR13>3.0.CO;2-1

Issue

Cancer

Cancer

Volume 79, Issue 1, pages 90–98, 1 January 1997

Additional Information

How to Cite

Egawa, S., Soh, S., Ohori, M., Uchida, T., Gohji, K., Fujii, A., Kuwao, S. and Koshiba, K. (1997), The ratio of free to total serum prostate specific antigen and its use in differential diagnosis of prostate carcinoma in japan. Cancer, 79: 90–98. doi: 10.1002/(SICI)1097-0142(19970101)79:1<90::AID-CNCR13>3.0.CO;2-1

Author Information

  1. 1

    Department of Urology, Kitasato University School of Medicine, Sagamihara, Japan

  2. 2

    Department of Urology, Hyogo Medical Center for Adults, Akashi, Japan

  3. 3

    Department of Pathology, Kitasato University School of Medicine, Sagamihara, Japan

*Department of Urology, Kitasato University School of Medicine,1-15-1 Kitasato, Sagamihara, Kanagawa 228, Japan

Publication History

  1. Issue published online: 27 SEP 2000
  2. Article first published online: 27 SEP 2000
  3. Manuscript Revised: 20 SEP 1996
  4. Manuscript Accepted: 20 SEP 1996
  5. Manuscript Received: 21 JUN 1996

Funded by

  • Ministry of Health and Welfare of Japan (7-42)

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Keywords:

  • prostate carcinoma;
  • free prostate specific antigen;
  • total prostate specific antigen;
  • free to total prostate specific antigen ratio;
  • α1-antichymotrypsin;
  • nonpalpable cancer

The ratio of free to total serum prostate specific antigen (PSA) renders total PSA more useful in the diagnosis of patients with low-range total PSA and those clinically diagnosed with benign prostatic hyperplasia.

Abstract

BACKGROUND

To improve the clinical usefulness of prostate specific antigen (PSA), unique methods have been proposed. The percentage of free PSA in serum facilitates the distinction between benign histologic conditions and prostate carcinoma while retaining high sensitivity.

METHODS

Using monoclonal antibodies, an AIA total PSA assay system was established that recognized PSA equally in free or complex form. The clinical usefulness of the ratio of two different molecular forms of PSA was investigated using 268 archival serum samples.

RESULTS

Men with prostate carcinoma had significantly lower ratios of free to total PSA than those with benign prostatic hyperplasia (BPH) (P = 0.0001). At total PSA levels between 2.1 and 10 ng/mL, medians of total PSA were not significantly different between men with prostate carcinoma and men with BPH. Differences in median percentages of free PSA for these two groups were statistically significant (P = 0.0001). The ratio of free to total PSA was useful for identifying prostate carcinoma in palpably benign glands with total PSA of 2.1-10 ng/mL (P = 0.0001), whereas total PSA was not useful for such identification. When calculated for low total PSA levels between 2.1 and 4 ng/mL, sensitivity and specificity were 91.7% and 72.2%, respectively, with a cutoff value of 17%. This ratio of free to total PSA was as useful as PSA density in receiver-operating curve analysis.

CONCLUSIONS

The use of the ratio of free to total PSA renders total PSA of greater use for distinguishing prostate carcinoma and is applicable to patients with low total PSA. Elderly men with a clinical diagnosis of BPH who are scheduled for surgery may benefit from the determination of this ratio. Cancer 1997; 79:90-8. © 1997 American Cancer Society.

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