Evidence mounts that rise in metastatic prostate cancer is linked to PSA screening reduction

Epidemiologic evidence presented during the 2021 Genitourinary Cancers Symposium provides teeth to the argument suggested in other recent analyses that the reduction in prostate-specific antigen (PSA) screening over that past decade is likely directly responsible for the rise in cases of metastatic prostate cancer in the United States.¹

Vidit Sharma, MD

“To reduce the incidence of metastatic prostate cancer in the United States, we support policies that promote shared decision making to optimize PSA screening, such as the updated USPSTF guidelines,” presenting study author Vidit Sharma, MD, a chief resident in the Department of Urology at Mayo Clinic, said during a poster presentation of the data.

PSA screening was found to reduce metastases and mortality in patients with prostate cancer, according to results from the randomized ERSPC trial. However, screening has also been known to result in significant harms from overdiagnosis and overtreatment of low-risk prostate cancer, Sharma noted. As a result, the USPSTF found insufficient evidence to recommend PSA screening in 2008 and went on to recommend against it in 2012.

“Several subsequent studies have found that there has been a rise in prostate cancer diagnosis since that change,” Sharma said. “Although the implication of these studies is that decreases in PSA screening were responsible for the rise in metastases, this has not been directly demonstrated.”

The objective of this study was to test the hypothesis that reductions in PSA screening were responsible for increased incidence of metastatic prostate cancer at diagnosis. To do this, investigators examined statewide variation in PSA screening, as well as statewide variation in the incidence of metastatic disease at diagnosis from 2002 to 2016.

Investigators extracted age-adjusted incidence of metastatic prostate cancer diagnosis per 100,000 men from the North American Association of Central Cancer Registries for each state. Additionally, survey-weighted PSA screening estimates for men 40 years of age or older were extracted from the Behavioral Risk Factor Surveillance System, which collected data on PSA screening every 2 years from 2002 onward.

These data were then analyzed in a multi-panel time series by state, using a random effects linear regression model, which looked at random effect at the state level, as well as related changes in PSA screening to incidence of prostate cancer metastases within and between states.

Results showed a significant variation in the incidence of PSA screening between states in men aged 40 years or older (range, 40.1%-70.3%). However, after 2010, a significant decrease in the median percentage of PSA screening across all states (range, 61.8%-50.5%) was observed. Additionally, investigators also noted a significant variation in the incidence of age-adjusted metastatic prostate cancer at diagnosis by state (range, 3.3 to 14.3 per 100,000 men) until 2010, when median incidence increased across all states.

Investigators found that states with larger decreases in PSA screening, there was a larger increase in the incidence of metastatic prostate cancer at diagnosis. Data from the random effects linear regression model confirmed that reductions in PSA screening were related to rises in metastatic disease at diagnosis (-14.9; 95% CI, 12.3-17.5 per 100,000; P <.01).

“Overall, variation in PSA screening explained 27% of variation in metastatic disease at diagnosis,” Sharma concluded.

Reference

1. Vidit Sharma, Abhishek Venkataramana, et al. Association of reductions in PSA screening across states with increased metastatic prostate cancer in the United States. J Clin Oncol. 2021;39(suppl 6):228. doi:10.1200/JCO.2021.39.6_suppl.228