An increasing percentage of men over the age of 75 who are diagnosed with prostate cancer have distant metastases at the time of diagnosis, according to a new study. No such increase was seen in younger men, and researchers think this could reflect changing prostate-specific antigen (PSA) screening guidelines.
“Following the introduction of PSA screening in the early 1990s, there has been a 50% decline in prostate cancer–specific mortality and more than a 70% decline in the incidence of metastasis at diagnosis,” wrote study authors led by Jim C. Hu, MD, MPH, of Weill Cornell Medicine–New York Presbyterian Hospital. In 2008, the US Preventive Services Task Force recommended against screening in men aged 75 or older, and in 2012, it recommended against PSA screening regardless of age, noting that the reduction in prostate cancer mortality is “at most, very small.”
The new study included 1,107,111 men in the SEER database, aged 40 and older, diagnosed with prostate cancer between 2004 and 2013. The results were stratified between men aged 75 years or older and those younger than 75; the study was published online ahead of print in JAMA Oncology.
In men younger than 75, the percentage presenting with metastases rose from 2.7% in 2004 to 4% in 2013 (P < .01), and the proportion with intermediate- or high-grade disease rose from 46.3% to 56.4% (P < .01). However, an adjusted analysis showed no significant change in the rate of distant metastases.
In older patients, 6.6% of men presented with distant metastases in 2004 compared with 12% in 2013, and this did remain significant in the adjusted analysis. The rate of intermediate- or high-grade disease also rose from 58.1% to 72% (P < .01) in these men.
The median PSA at diagnosis increased from 6.0 ng/mL in 2010 to 6.4 ng/mL in 2013 in younger patients; in older men, the median PSA rose from 9.0 ng/mL to 9.7 ng/mL (P < .01 for both).
“Although we demonstrate an increase in the incidence of distant metastases at diagnosis in men 75 years or older, we did not examine prostate cancer–specific mortality, which requires longer observation before meaningful differences can be discerned,” the authors wrote.
In an accompanying editor’s note, Charles R. Thomas Jr, MD, of Oregon Health Sciences University in Portland, and Yu Shyr, PhD, of Vanderbilt University in Nashville, wrote that these results contradict an earlier study showing distant metastases have not changed in recent years; they suggest that this could be merely statistical random variation. “The impact on mortality from screening is not well defined,” they wrote. “Hence, clinicians will need to be cautious in their interpretation of the screening as well as treatment guidelines for the individual patient in front of them.”