More intensive prostate cancer screening can reduce the risk of metastatic cancer later in life

More intensive prostate cancer screening can reduce the risk of metastatic cancer later in life

Given conflicting evidence about the risks and benefits of routine prostate cancer screening, a large longitudinal analysis found that Veterans Health Administration (VA) medical centers with lower prostate screening rates had higher rates of metastatic prostate cancer cases in subsequent years than centers with higher screening rates. The results of the study will be presented today at the annual meeting of the American Society for Radiation Oncology (ASTRO) and published in JAMA Oncology.

This study provides evidence that facilities that screen men more intensively may reduce the later risk of metastatic prostate cancer.”

Alex K. Bryant, MD, lead author of the study and a resident radiation oncologist, University of Michigan Rogel Cancer Center in Ann Arbor, Mich.

Although the study was not a randomized clinical trial - the gold standard for guiding clinical practice - the results are based on real-world evidence that can help guide screening decisions for patients that weigh individual risks and benefits. "If someone had a strong family history of prostate cancer or other risk factors and wanted to reduce their risk of metastatic prostate cancer, these results could support the decision to screen," said Dr. Bryant.

To date, the two largest studies of prostate cancer screening - both randomized controlled trials - have provided conflicting evidence about the risks and benefits of prostate-specific antigen (PSA) testing, with one study suggesting that PSA screening reduces the risk of metastatic prostate cancer and prostate cancer death and another showing no benefit. Since 2008, conflicting data and corresponding changes in clinical practice guidelines have resulted in a decline in PSA screening rates across the country, followed by an increase in the incidence of metastatic prostate cancer. However, there is currently no evidence of a connection between the two trends.

“Conflicting research findings have understandably led to reasonable variations in screening patterns,” said Dr. Bryant. "Doctors have very different views on the risks and benefits of prostate cancer screening. Some doctors believe the benefits of screening far outweigh the risks of false positives." But others don’t.”

“Given the equivocal clinical trial data on the effectiveness of PSA screening,” he continued, “we hoped to see whether we could find an association suggesting that screening might impact rates of metastatic prostate cancer in the real world.”

The team analyzed data from 128 facilities in the VA Health System, the largest integrated health system in the United States. In 2005, when the study began, there were 4.7 million men in the cohort. By the end of the study in 2019, the cohort had grown to 5.4 million men.

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Researchers analyzed annual PSA screening rates at the facility and system levels; long-term system and facility-level non-screening rates; and age-adjusted incidence rates of metastatic cancer from 2005 to 2019. Cases of metastatic cancer were identified using diagnosis codes and a validated natural language processing algorithm sorted through physician-recorded notes and radiographic reports.

PSA screening rates declined systemwide from 47% in 2005 to 37% in 2019, and this decline was seen across all age groups and races. During the same period, long-term non-screening rates—the percentage of patients who missed screenings three years in a row—increased across the VA health system.

Overall, the incidence of metastatic prostate cancer increased from 4.6 cases per 100,000 men in 2008 to 7.9 per 100,000 in 2019. The increase was driven by increases in the 55-69 and over 70 age groups.

Facilities with lower annual screening rates had higher subsequent rates of metastatic prostate cancer. For every 10% decrease in screening, there was a corresponding 10% increase in the incidence of metastatic prostate cancer five years later (incidence rate ratio 1.10, 95% confidence interval [CI] 1.04-1.15, p<0.001).

In addition to the trend in annual rates, there was also an association between long-term non-screening rates and subsequent incidence of metastatic cancer. For every 10% increase in long-term nonscreening rates, there was an 11% increase in the incidence of metastatic prostate cancer (95% CI 1.03 to 1.19, P = 0.010).

It's important to gain a deeper understanding of the risks and benefits of screening because once prostate cancer spreads to other parts of the body, "it is generally considered to be at an incurable stage," said Dr. Bryant. “It is still treatable, but once it spreads it is a fatal disease.

He said the team will continue to analyze VA records to assess whether screening rates are linked to prostate cancer mortality. Further analyzes will also include racial and ethnic differences in PSA screening rates and potential differences in how screening affects long-term outcomes in high-risk groups. Of particular interest is how screening rates and outcomes may differ for black patients, as black men are twice as likely to die from prostate cancer compared to men of other races.

“This study is the first step in a series of studies using VA data to provide more accurate information about populations at increased risk of prostate cancer,” he said.

Source:

American Society for Radiation Oncology

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