Cases of metastatic prostate cancer are on the rise since the U.S. Preventive Services Task Force (USPSTF) recommended against routine PSA (prostate specific antigen) screening in men over age 75 in 2008 and in all men in 2012. This disconcerting news comes from a study in JAMA Network Open that was released in March, but it was not a big surprise to many experts who had predicted such an outcome.
The USPSTF made those recommendations out of concern at the time that the PSA test, which can detect early prostate cancer, resulted in too many false positives, leading to overdiagnosis and overtreatment of low-risk cancers that would be unlikely to turn deadly—not to mention complications from treatment (notably incontinence and erectile dysfunction) and undue worry many men experience after a positive test result. That is, the risks of routine screening were deemed to outweigh the benefits. Though the 2008 and 2012 recommendations have since been replaced (see below), sharp drops in PSA screening have been noted in the years after they were issued, especially after 2012.
To determine the incidence of metastatic prostate cancer before and after these USPTF recommendations, researchers at the University of Southern California used a large national government cancer database that included information on more than 830,000 men ages 45 and older who were diagnosed with prostate cancer between 2004 and the end of 2018. Of them, 26,642 men ages 45 to 74, and 20,507 men ages 75 and older, were diagnosed with metastatic disease.
Adjusting for age and race (two factors that play a role in the development of prostate cancer), the researchers found that the incidence of metastatic disease did not change from 2004 to 2010 in the younger group and even went down in the older men in roughly that same period. But cases climbed significantly from 2010 to 2018 in both age groups: 41 percent in men 45 to 74 (5.3 percent annually) and 43 percent in those 75 and over (6.5 percent annually); the increase was greater in older and non-Hispanic white men. The findings contrast with an overall decline in prostate cancer diagnosis seen over these years, as would be expected with reduced PSA screening.
The timing of these findings strongly suggests that the rise in metastatic prostate cancer was due to decreased PSA screening, as was advocated by the USPSTF. Although there may be other reasons behind the upward trend, the authors of the paper contend that “it is unlikely to be due to a true change in cancer biology in such a short period.” Neither is it likely to be due to environmental exposures, which would take longer to manifest as cancer. Other countries that have followed the USPSTF recommendations have reported similar trends, the paper also notes.
Where things stand now. In 2018, the USPSTF walked back its prior recommendations, replacing them with individual decision-making for men ages 55 to 69. That was because more evidence had come out showing the benefits of early detection for reducing metastatic prostate cancer diagnoses and mortality in some men. The 2018 update states that men should have an opportunity to discuss the potential harms and benefits of prostate cancer screening with their doctor, taking into consideration their family history, race/ethnicity, comorbidities, personal values, and other health factors. “This revised guideline should be encouraging clinicians to more consistently address screening with men who are healthy enough to benefit, engaging them in shared decision-making discussions to determine their screening preferences,” a commentary accompanying the new study stated. However, the USPSTF continues to recommend against PSA screening in older men, with the age dropped even lower—from 75 to 70.
If more men opt for PSA screening again, time will tell if that translates into fewer cases of metastatic cancer down the road. In the meantime, the potential harms of screening may be lower now as diagnostic tests continue to improve and as the practice of active surveillance after diagnosis increases.
