1) The accuracy of the PSA test for detecting prostate cancer depends on the age of the patient and the prevalence of prostate cancer, which increases significantly with age. 2) For patients under 70 years old, the PSA test has very low accuracy, ranging from near 0% to 22% accuracy, which could lead to many unnecessary invasive biopsies. 3) The U.S. Preventive Services Task Force recommends against PSA-based prostate cancer screening for men 75 and older, and makes no recommendation for men under 75 due to inadequate evidence that screening improves health outcomes.

1. PSA Test accuracy Gaetan “Guy” Lion July 2010

4. Prostate Cancer Incidence Rate Those incidence rates look very small. But, on a cumulative basis they translate into material prevalence rates as one ages as shown on the next slide.

5. Prostate Cancer Prevalence Rate At 45 years old very few men have prostate cancer. By 85, nearly a quarter of them do have it. The age specific prevalence rate of prostate cancer is a material driver of the accuracy of the PSA test. The higher the prevalence rate the more accurate the PSA test.

6. PSA Test Accuracy with high Prevalence The high end prevalence is 23.4% associated with 85 years old. In such a case, a positive test is 50% accurate.

7. PSA Test Accuracy across Prevalence Rates Using the same Bayesian logic as on the previous page, we can see how the test accuracy when positive decreases very quickly when the age-specific prevalence drops and vice versa.

8. PSA Test Accuracy vs Prevalence Rate Accuracy goes up as the age specific prevalence rate goes up. But, at the high end of prevalence rate (for 85 years old) a positive test is still no more accurate than a flip of the coin.

9. PSA Test Accuracy vs Age Bucket For anyone under 70 years old, the PSA test (positive result) is highly inaccurate (accuracy ranging from near 0% to only 22%). This will cause a lot of unnecessary biopsies.

11. U.S. Preventive Services Task Force (USPSTF) Recommendation For men 75 years or older, the USPSTF, explicitly recommends no screening. For men under 75 years, the USPSTF makes no recommendation because “the evidence is inadequate to determine whether screening improves health outcomes.” Per the USPSTF, harms of treatment include erectile dysfunction, urinary incontinence, bowel dysfunction, and death. A proportion of those treated would never have developed cancer symptoms during their lifetime.