Testosterone Levels In Benign Prostatic Hypertrophy And Prostate Cancer

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Clinical Trials / Drug Trials
Article Date: 03 May 2008 - 0:00 PDT

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UroToday.com - The introduction of PSA for the diagnosis of prostate carcinoma has undoubtedly increased the detection rate of localized tumours. As PSA has low specificity, particularly in screening programmes, surrogates are being sought e.g. PSA density, velocity or free/total ratio. Despite this, a reliable, easy to use, marker of prostate cancer still remains to be found.

Circulating androgens, particularly testosterone, are known to play fundamental roles in prostate growth. The underlying mechanism of action remains to be identified because androgen mediates complex interactions among many prostate growth factors, hormones and cell lines. Prostate cancer has often been associated with low testosterone levels: testosterone concentrations drop with age and the incidence of prostate cancer is greatest in elderly patients.

128 patients were studied because of BPH or prostate cancer. Blood samples were drawn from each patient to determine baseline total testosterone T, FSH, LH and PRL.

Mean serum testosterone concentrations were significantly higher in patients with BPH than in those with prostate cancer (4.7 ng/ml vs 3.3 ng/ml; p<0.05). Moreover, 37% of patients with prostate cancer had below normal testosterone levels i.e. < 2.4 ng/ml and 26% reached the castration threshold of <0.5 ng/ml. Only 9% of patients with BPH had below normal testosterone levels (none of whom reached the castration threshold).

At multivariate analysis, including age, prostate volume, PSA and DRE, the overall goodness of fit was 85.8%; it was 80.0% for prostate cancer and 91.9% for BPH. Prostate volume and PSA reached statistical significance, as they are independent predictors of disease. In a second model, testosterone values were added as a continuous variable: the overall correct estimate was 89% (86.2% for prostate cancer; 91.9% for BPH). Testosterone approached statistical significance as an independent predictor of disease status (p=0.065). The third model included age, prostate volume, PSA and DRE with testosterone as a binary (cut-off 2.4 ng/ml, the lower value of the test used) rather than continuous variable. The overall correct estimate was 90.6% (86.2% for prostate cancer; 95.2% for BPH). Testosterone reached statistical significance and became an independent predictor of disease status (p<0.05). The odds ratio of testosterone levels for prostate cancer was 0.147 (95% C.I. 0.03-0.68), suggesting the higher the testosterone level the lower the risk of prostate cancer. The AUC of Testosterone <= 2.4 ng/ml was 0.965 (95% C.I. 0.896-1.000; p<0.01). The AUC of Testosterone > 2.4 ng/ml was 0.507 (95% C.I. 0.389-0.624; p=0.913).

The present paper provides evidence that prostate cancer is associated with lower testosterone levels than BPH. As our patients with prostate cancer have lower testosterone levels than patients with BPH, could testosterone levels have a potential diagnostic value? Our multiple logistic regression models shows that testosterone reached statistical significance and became an independent predictor of disease status, and suggests the higher the testosterone levels the lower the risk of prostate cancer. At the 2.4 ng/ml cut-off sensitivity was 36.9% and specificity 99.0%!

However, our study has some limitations. Since patients with symptomatic BPH were included, the results may not necessarily apply to a screened population. Furthermore, follow up may be too short to assessing prostate cancer occurrence in so-called "BPH group". Most important, the limited number of patients we recruited add a limitation to our conclusion, especially in designing a specific nomogram. However, these interesting preliminary results suggest a Testosterone test should be included in baseline evaluation of every patient with prostate disease.

Written by Luigi Mearini, MD, as part of Beyond the Abstract on UroToday.com

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