People living with HIV (PWH) have higher risk for many cancers than the general population. However, prostate cancer is a notable exception, as incidence in PWH in the US is approximately half of the incidence in the general population.1 It has been difficult to establish whether this decreased risk is an artifact of lower rates of PSA screening among PWH, or alternatively caused by potential biological mechanisms that reduce risk.
To carefully study the role of PSA screening requires cohort studies that include both PWH and HIV-uninfected people and also have detailed information on PSA testing. There are several questions to address, including whether rates of PSA testing are lower among PWH, whether the difference in prostate cancer incidence changes after accounting for screening, and whether the incidence of advanced prostate cancer (which is not usually screen-detected) differs by HIV status.
The study by Leapman et al analyzed PWH and HIV-uninfected individuals in the Veterans Aging Cohort Study. Although veterans should have uniform access to care, the adjusted rates of PSA screening were 13% lower in PWH. Prostate cancer incidence among PWH was 10% lower than uninfected individuals, but this difference attenuated to 7% after adjustment for PSA testing and was no longer statistically significant. There was no evidence of stage differences by HIV status.
Among prior studies, two concluded that PSA screening does not fully explain lower prostate cancer incidence among PWH, based on reductions in risk for late-stage tumors1 or persistence of reduced risk after restriction to men who received a PSA test.2 Importantly, the relationship between HIV status and the rate of PSA testing varies across populations, and therefore its role in explaining reduced prostate cancer incidence may vary as well. The study by Leapman et al suggested that differential PSA testing played a partial role, but the lack of statistical significance after adjustment does not rule out a residual difference in prostate cancer incidence between PWH and HIV-uninfected men.
More detailed epidemiological analyses could continue to shed light on this question in the future. These could include comparisons of incidence among men who never received PSA testing, or comparisons of non-screen-detected cases (e.g., symptomatic cases).
Footnotes
Disclaimer: Where authors are identified as personnel of the International Agency for Research on Cancer / World Health Organization, the authors alone are responsible for the views expressed in this article and they do not necessarily represent the decisions, policy or views of the International Agency for Research on Cancer / World Health Organization.
Conflicts of interest: None
References
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