NEW YORK (Reuters Health) – Men ages 75 to 80 years old with a prostate specific antigen (PSA) level less than 3 ng/mL are unlikely to experience life-threatening prostate cancer during their remaining life span, according to findings from the Baltimore Longitudinal Study of Aging, published in the Journal of Urology for April.

“Therefore,” Dr. Edward M. Schaeffer and co-authors conclude, “these men may represent an ideal target group for discontinuation of PSA testing, which could dramatically reduce the costs associated with screening, as well as the potential morbidity of additional evaluations and/or treatment in a population unlikely to experience benefit.”

Although the optimal age for stopping PSA screening is controversial, they add, screening rates in elderly men are high, often exceeding rates among those in their 50s.

The study included 849 men aged 40 years and older with serial PSA measurements. Of 122 with prostate cancer, 35 cases were deemed high risk based on a PSA of 20 ng/mL or higher, a Gleason score of 8 or greater, or death from prostate cancer; 18 died.

“Of the 154 participants older than 75 years with PSA less than 3 ng/mL, none died of prostate cancer and high risk prostate cancer developed in only 1,” Dr. Schaeffer, at Johns Hopkins School of Medicine, and his team report. This latter patient had a PSA of 2.9 ng/mL, but did not die of his disease.

Five other men had non-high-risk prostate cancer after age 75, with PSAs of no higher than 3 ng/mL. Four died of other causes, while the remaining subject remains alive 8 years after receiving his diagnosis.

“If confirmed, these findings may be useful in determining more concrete guidelines for when PSA based screening might be safely discontinued,” the investigators suggest. They still advise PSA testing for symptomatic men, regardless of their age.

However, authors of two editorial comments take issue with the investigators’ conclusions.

Dr. Peter C. Albertson at the University of Connecticut Health Center, Farmington, suggests that any PSA screening over the age of 75 “may prevent a few deaths from prostate cancer (but) this comes at an enormous cost in testing and treatment.”

Dr. Ruth Etzioni at Fred Hutchinson Cancer Research Center, Seattle, warns against “going directly from data to policy using observational data,” especially when based on a post hoc observation. Instead, she advocates developing policy “by integrating multiple studies with techniques such as decision analysis or outcomes modeling.”

Reference:
J Urol 2009;181:1606-1614.