More intensive screening for prostate cancer may reduce the risk of metastatic cancer later

In the face of conflicting evidence on the risks and benefits of routine prostate cancer screenings, 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. Study results will be presented today at the American Society for Radiation Oncology (ASTRO) annual meeting and are published in JAMA Oncology.

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


Alex K. Bryant, MD, study lead author and resident radiation oncology physician, University of Michigan Rogel Cancer Center in Ann Arbor, Michigan.

Although the study was not a randomized clinical trial – the gold standard for clinical practice guidance – the results are based on real-world evidence that can help guide screening decisions for patients by assessing the 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 get screened,” said the Dr Bryant.

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

“Contradicting research results have naturally led to reasonable variations in screening regimens,” Dr. Bryant said. “Doctors have very different feelings about the risks and benefits of prostate cancer screening. Some doctors feel that the benefits of screening far outweigh the risks of false positives.” Others, however, do not.”

“Given the ambiguous clinical trial data on the effectiveness of PSA screening,” he continued, “we hoped to see if we could find an association suggesting that screening might affect 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.

The researchers analyzed annual PSA screening rates at the facility and system level; long-term non-test rates at the system and facility level; and age-adjusted metastatic cancer incidence rates from 2005 to 2019. Metastatic cancer cases were identified using diagnosis codes and a validated natural language processing algorithm that was selected from notes recorded by the doctor and X-ray reports.

PSA screening rates declined system-wide from 47% in 2005 to 37% in 2019, and this decline was seen across all ages and races. During that same period, long-term miss rates — the percentage of patients who missed screenings for three consecutive years — 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. This increase is due to increasing age groups 55 to 69 year olds and over 70 year olds.

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

In addition to the trend in annual rates, there was also an association between long-term non-screening rates and later incidence of metastatic cancer. For every 10% increase in long-term unscreened 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 better understand the risks and benefits of screening because once prostate cancer spreads to other parts of the body, “the general thinking is that it’s at an incurable stage,” he said. Dr Bryant. “It’s still treatable, but once it spreads it’s a fatal disease. Our results support a benefit in prostate cancer screening by reducing the risk of metastatic prostate cancer.”

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

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

Source:

American Society of Radiation Oncology