麻豆传媒

The rates of prostate-specific antigen (PSA) screening, prostate biopsy, and treatment of prostate cancer have all declined significantly since the publication of the United States Preventive Services Task Force (USPSTF) against PSA-based screening for prostate cancer, an analysis of privately insured men in the United States has shown.

In a large cohort of approximately six million men, researchers found that PSA testing, prostate biopsy, and prostate cancer detection rates all dropped significantly between 2009 and 2014 -- most notably after 2011, when the USPSTF recommendations were first reported by the lay press, James Kearns, MD, of the University of Washington School of Medicine in Seattle, and colleagues wrote online in .

"In addition to finding decreased prostate cancer screening, we found that fewer men were being diagnosed with prostate cancer and even fewer men were being treated with surgery or radiation for their prostate cancer," Kearns said in a statement. "This means they are likely choosing active surveillance for low-risk prostate cancer, which is important because active surveillance has been shown to be safe in many men and it avoids problems associated with prostate cancer treatment such as urinary incontinence and erectile dysfunction."

For the study, the researchers used the MarketScan database to identify men between ages 40 and 64 who are insured through large employers and who had a full year of data that could be analyzed.

"We examined several outcomes that we hypothesized may be impacted by the USPSTF statement on PSA screening, including PSA testing, rate of prostate needle biopsy, incident prostate cancer, and prostate cancer treatment," the investigators explained. Definitive treatment included either radical prostatectomy, external-beam radiation therapy, or brachytherapy.

"The proportion of prostate needle biopsies performed per 100 PSA tests decreased significantly over the study period (P<.01)," the team reported. For example, in 2009, the adjusted relative rate for prostate biopsies per 100 PSA tests was 1.91 (95% CI, 1.89 to 1.93). In 2012, that rate had fallen to 1.59 prostate biopsies per 100 PSA tests (95% CI 1.66 to 1.70), and by 2014, the rate had fallen further to 1.52 biopsies per 100 PSA tests (95% CI 1.50 to 1.54).

Conversely, the incidence of prostate cancer for each prostate biopsy increased slightly over the same study interval, from 0.36 (95% CI, 0.35 to 0.36) in 2009 to 0.39 (95% CI, 0.39 to 0.40) in 2014. The rates of local treatment for each diagnosis of prostate cancer followed a similar declining trajectory, from 0.67 (95% CI, 0.66 to 0.67) in 2009 to 0.54 (95% CI, 0.53 to 0.55) in 2014, while the number of men who underwent PSA screening for each prostate cancer diagnosis made increased from 141 (95% CI, 138 to 143) in 2009 to 161 (95% CI, 157 to 164) in 2014.

"Of new prostate cancer diagnoses, the proportion managed with definitive local treatment decreased from 69% (95% CI, 69%-70%) to 54% (95% CI, 53%-55%) [across the study interval]," the researchers said. "And the trends we observed were true across all age strata, including men younger than 60."

Study limitations, the authors noted, included a lack of information in the MarketScan database about race, socioeconomic status, pathologic parameters, and PSA levels.

Writing in an , Christopher Filson, MD, of Emory University School of Medicine in Atlanta, agreed that that there is "substantial" evidence that PSA screening rates have been dropping since the USPSTF recommendation against PSA screening, with the largest decreases among men between 60 and 64.

On the other hand, Filson acknowledged concerns that decreased detection of early-stage prostate cancer may result in higher rates of metastatic prostate cancer on diagnosis, which the authors themselves flagged as a possible public health consequence of lower PSA screening and early cancer detection rates. For example, an evaluation of the National Cancer Database suggested that there has been at least a 7% annual increase in the number of metastatic prostate cancer cases between 2007 and 2013.

"Paradoxically, this analysis revealed that the most dramatic increases in metastatic prostate cancer diagnoses were among patients age 55 to 69, who were not subjected to changes in PSA screening recommendations before 2011," Filson wrote. "This group would not have had the lead time from changes in PSA screening to eventual development of metastatic disease."

Furthermore, another did not demonstrate an increase in the incidence of metastatic prostate cancer in the years after the USPSTF recommendations, although there seemed to be a suggestion of an in metastatic prostate cancer incidence in men over the age of 75 after 2011, Filson pointed out.

In addition, greater access to healthcare may also have influenced the number of new metastatic prostate cancers diagnosed after 2012: "It is estimated that 7.6 million men ages 35-64 gained coverage between 2010 and 2015, and many of those men who suddenly had access to healthcare were previously under-insured or uninsured.

"An uptick in metastatic prostate cancer diagnoses with more interactions between patients and healthcare providers is a reasonable possibility, Clearly, existing evidence of a link between the USPSTF PSA screening recommendations and subsequent changes in the incidence in metastatic disease is mixed, at best."

He said that given that PSA screening needs a lead time of approximately 5 to 7 years for an earlier diagnosis, "one would hypothesize that any signal of increased incidence of metastatic prostate cancer would not be seen for at least that amount of time."