Reduced PSA Screening Rates Associated with Rise in Metastatic Prostate Cancer: JAMA

SAN ANTONIO: A recent study reported in JAMA Oncology revealed that lower prostate-specific antigen (PSA) screening rates were linked to later higher risks of metastatic prostate cancer.

The study team noted that although no causal conclusions can be made from the current investigation, they did observe a relationship between lower facility-level PSA screening rates and greater risk of metastatic prostate cancer later on.

The advantages of prostate-specific antigen (PSA) screening are debatable. In the US, the prevalence of metastatic prostate cancer has grown while the rates of prostate-specific antigen screening have declined since 2008. However, there is no direct epidemiologic proof that the prevalence of PSA screening in the population and the incidence of metastatic prostate cancer are correlated.

The researchers sought to determine whether variations in PSA screening rates at the facility level are linked to a subsequent occurrence of metastatic prostate cancer there.

"Our data are far more in line with the European trial's findings, which supported the value of PSA screening. And it does corroborate the theory that the American study's lack of a significant difference was due to the fact that both the control and intervention arms underwent a significant amount of PSA screening. Essentially, PSA screening was conducted on both sides of the group." the authors said.

The researchers examined information on yearly PSA screening rates at the facility and system levels, long-term non-screening rates at the system and facility levels, and age-adjusted incidence rates of metastatic cancer from 2005 to 2019 from 128 facilities in the VA health system. Cohort size increased from 4.7 million men at the start of the study in 2005 to 5.4 million men by the time it was completed in 2019. In 2012, there were 9.2% of Black patients on average, compared to 76.7% white patients. A median 33.9% of patients were 70 years of age or older. The main outcomes included facility-level annual counts of incident metastatic prostate cancer diagnoses and age-adjusted annual incidence rates of metastatic prostate cancer (per 100 000 men) 5 years after each exposure to PSA screening.

Key results of the study:

• All ages and races saw a decrease in PSA screening rates from 47% in 2005 to 37% in 2019.
• The percentage of patients who have not had a PSA test in the past three years, or long-term non-screening rate, rose from a low of 20.9% in 2009 to a high of 33.2% in 2019.
• Men in the 55–69 and over–70 age categories were mostly responsible for the increase in age-adjusted metastatic prostate cancer incidence rates, which increased from 4.6 cases per 100,000 men in 2008 to a high of 8.2 cases per 100,000 men in 2017.
• At five years, greater long-term non-screening rates were linked to higher incidence rates of metastatic prostate cancer (IRR 1.11 per 10% increase in long-term non-screening rate, 95% CI 1.03-1.19, P=0.01).
• Higher PSA screening rates at the facility level were linked to decreased rates of metastatic prostate cancer five years later (incidence rate ratio [IRR] 0.91 per 10% increase in PSA screening rate, 95% confidence interval [CI] 0.87-0.96, P0.001).

The data could be used to help men who want to lower their risk of metastatic prostate cancer make informed decisions regarding the potential advantages of PSA screening, the authors concluded.

They emphasized that while there is a risk of overdiagnosis and overtreatment, there is also a risk of underdiagnosis and undertreatment if PSA screening is completely abandoned.

REFERENCE

Bryant AK, et al "Association of prostate-specific antigen screening rates with subsequent metastatic prostate cancer incidence at US Veterans Health Administration facilities" JAMA Oncol 2022; DOI: 10.1001/jamaoncol.2022.4319