Incidence of False Negative Prostate Cancer Screening in Patient Taking 5-Alpha Reductase Inhibitors
Prostate specific antigen (PSA) is increasing controversial, but remains the most common tool for prostate cancer screening, with 34-50% of men aged 55-70 having been screened in 2013. Many of these men take a 5-alpha reductase inhibitor (5-ARI) for management of benign prostatic hyperplasia (BPH). These medications inhibit the conversion of testosterone to dihydroxytestosterone, removing the primary trophic factor for the prostate and decreasing the systemic PSA. We hypothesized that this interaction would lead to false negative screening tests.
Using a database query software designed at our institution, we collected the first screening PSA test for all men screened from 2014 to July of 2017 taking a 5-ARI in the year prior. Men with a diagnosis of prostate cancer prior to the first PSA test were excluded from the analysis. Published normal values were used and patients taking a 5-ARI had their result doubled. Manual chart review was then used to determine if the provider who ordered the screening test was aware of the effect of the 5-ARI. SPSS v20 was used for all statistics.
A total of 29,131 men met inclusion criteria. Of these men 1,654 (5.7%) were prescribed a 5-ARI in the 12 months prior to the incident PSA screening test, with 118 (7.1%) of these having a value that would be positive only if corrected for 5-ARI use. On chart review 33 (27.9%) of these patients had no indication that the provider had noted this. We also found that discordance between the provider for PSA and 5-ARI had no effect on rates of false negative values (p = 0.837) (Table 1a). Interestingly, if the provider who ordered the PSA test was a urologist/urology care extender the likelihood that a false negative value would be identified was much lower (p=0.001) (Table 1b).
More than a quarter of men with false negative screening tests were missed by the ordering provider. This happened more often when the ordering provider was not a urologist or urology care extender. Interestingly, discordance between the providers ordering the 5-ARI inhibitor and the PSA screen did not appear to be related to rates of missed false positives, implying that communication between providers is not a major contributor to this issue. An opportunity exists to improve the quality of PSA testing by preventing false negative tests.