Drops in routine PSA screenings over the last few years may have spurred an increase in metastatic prostate cancer, according to a new study out of Keck Medicine of the University of Southern California.

In 2008, the United States Preventive Services Task Force recommended that men over 75 not undergo routine PSA screenings due to the risks for overdiagnosis and overtreatment of low-risk prostate cancer. It followed up in 2012 with the same guidance for all men, despite the fact that previous studies showed a drop in both metastatic prostate cancer and prostate cancer death with such screenings.

In their study, Keck Medicine researchers found discrepancies in metastatic case rates from before and after the policy changes, with incidents for men both under and above 75 going up by more than 40% each. The findings, they say, are significant because when caught early through screening, prostate cancer is often treatable and curable.
"The study in itself cannot make recommendations on screening policy as that is a broader issue. What we have been able to show is a persistent rise in metastatic prostate cancer coinciding with recommendations against screening. The USPSTF has already modified its recommendations against screening in all men (D) to informed decision making in Men 55-74 (category C)," Dr. Mihir Desai, MPH urologist and director of robotic surgery with USC Urology and one of the first authors of the study, told HCB News.

The authors sifted through more than 836,000 prostate cancer cases from 2004 to 2018 through the Surveillance, Epidemiology and End Results (SEER) Program cancer incidence database. Of these, 26,642 cases were metastatic and of men between 45 and 74. Another 20,507 showed the same status for men 75 and older.

The incidence rate for such cases in the 45 to 74 age group remained stable between 2004 and 2010, but increased by 41% between 2010 and 2018. For men, 75 and older, rates went down between 2004 and 2011, and then increased 43% between 2011 and 2018. Rises for both age groups affected all races.

The authors say that other factors, such as the use of new diagnostic and staging technologies for detecting low-volume metastatic prostate cancer, may have enabled greater detection of such cases and therefore contributed to the increases. But these techniques are not widespread and not typically used for first-time cancer detection.

They add that original evidence to suggest overdiagnosis and overtreatment of low-risk prostate cancer may also be outdated. "Many advances including biomarkers and MR may help select patients for biopsy that are more likely to have clinically significant cancer. Additionally, men with a longer life expectancy as well as high risk populations such as African Americans, family history of prostate cancer or familial history of germline mutations should be preferentially selected for screening," said Desai.

The findings were published in JAMA Network Open.

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