Predictive value of prostate specific antigen in a European HIV-positive cohort: does one size fit all?

BACKGROUND: It is common practice to use PSA≥4.0 µg/L as a clinical indicator for men at risk of PCa, however this is unverified in HIV + men. We aimed to describe kinetics and predictive value of PSA for prostate-cancer (PCa) in HIV+ men.

METHODS: A nested-case-control study of 21 men with PCa and 40 matched-controls within EuroSIDA was conducted. Prospectively stored plasma samples before PCa (or matched date in controls) were measured for the following markers: Total PSA[tPSA], free PSA[fPSA], testosterone and sex hormone binding globulin[SHB]. Conditional logistic regression models investigated associations between markers and PCa. Mixed models were used to describe kinetics. Sensitivity and specificity of using tPSA >4 µg/L to predict PCa was calculated. ROC curves were used to identify optimal cut-offs in HIV+ men for total PSA.

RESULTS: 61 HIV+ men were included with a median 6(IQR 2-9) years follow-up. Levels of tPSA increased by 13.7% per year (95%CI:10.3,17.3) in cases, but was stable in controls (-0.4%;95%CI:-2.5,1.7). Elevated PSA was associated with higher odds of PCa at first (OR for 2-fold-higher 4.7;95%CI:1.7-12.9;P<0.01) and last sample (8.1;95%CI:1.1,58.9;P=0.04). A similar relationship was seen between fPSA and PCa. Testosterone and SHBG level were not associated with PCa. tPSA level>4ng/mL had 99% specificity and 38% sensitivity. The optimal PSA cut-off was 1.5ng/mL overall (specificity=84%, sensitivity=81%).

CONCLUSIONS: PSA was highly predictive of PCa in HIV+ men; however the commonly used PSA>4ng/mL to indicate high PCa risk was not sensitive in our population and use of the lower cut-off of PSA>1.5ng/mL warrants consideration.