Assessing Risk: Does This Patient Have Prostate Cancer?

Extract

Prostate-specific antigen (PSA) is used routinely in the United States to screen for prostate cancer, a disease that accounts for a similar number of yearly male cancer deaths as colon and rectal cancers combined. PSA screening followed by prostate biopsy leads to the detection of early-stage prostate cancers for which a cure is more likely ( 1 ) . However, the extent to which PSA screening has influenced declining prostate cancer mortality rates in the United States and whether routine PSA screening improves overall health outcomes remain matters of debate.

Physicians (especially urologists) are aware that PSA test results, digital rectal examination (DRE) findings, family history of prostate cancer, and other risk factors (such as race) can influence the chance that prostate cancer will be found on a biopsy. Furthermore, because of the frequency of serial PSA testing, physicians now have a heightened suspicion of prostate cancer in men whose PSA level increases over time (referred to as PSA velocity). However, since 1989, when an assay manufacturer reported that a serum PSA level in the range of 0–3.99 ng/mL was “normal” ( 2 ) , PSA level has been used primarily as a dichotomous biomarker, with a threshold value of 4.0 ng/mL, as a prompt for recommending a prostate biopsy; urologists commonly recommend prostate biopsies (at least initially) when a man's PSA level exceeds this “normal” range, regardless of other risk factors. This approach has remained commonplace even though Gann et al. ( 3 ) in 1995 clearly showed that, during the 10 years following a baseline PSA measurement, the risk of being diagnosed with a life-threatening prostate cancer increased incrementally with increasing PSA levels that remained well below 4.0 ng/mL and cautioned that information would be lost by dichotomizing PSA test results.