Semi-annual PSA may be safe for men on surveillance

Chicago-Some men with low-risk prostate cancer who are being managed by active surveillance can have their PSA levels measured every 6 months instead of every 3 months, researchers reported at the American Society of Clinical Oncology annual meeting in Chicago.

No difference was seen between PSA doubling time measured every 3 months and every 6 months and in disease progression as reflected by PSA doubling time ≤3 years.

“This finding provides evidence that semi-annual PSA testing may be safe for some men on active surveillance,” wrote the authors, led by Matthew R. Cooperberg, MD, MPH, associate professor of urology at the University of California, San Francisco. Dr. Cooperberg presented the findings.

The authors explained that most active surveillance protocols require serial PSA assessment every 3 months, and many define disease progression according to PSA kinetics; in particular, PSA doubling time.

Because it is unclear whether PSA kinetics would differ if assessment occurred every 6 months or every 3 months, the authors conducted a study to compare PSA assessment at the two different time points in a cohort of 831 men participating in a prospective study of active surveillance called the Canary Prostate Active Surveillance Study (PASS). Disease progression was defined as a doubling of PSA.

PSA doubling time was calculated in all men every 3 months up to 42 months after diagnosis. Doubling time was assessed every 3 months and every 6 months in 205 of the 831 men in the PASS study. Progression was defined as PSA doubling time ≤3 years, while >3 years represented no progression.

Of the 205 men in the study cohort, 67% of patients were over 60 years of age, 92% were Caucasian, 92% had Gleason scores of <6, and 8% had Gleason 7 scores. Serum PSA levels were 0 ng/mL-3.99 ng/mL in 46%, 4.0 ng/mL-10.0 ng/mL in 47%, and >10.0 ng/mL in 6%. Eighty-six percent were clinical stage T1c, 12% were stage T2a, and 2% were T1a/b. Fifty-two percent had one to 10 positive cores on biopsy, 4% had 11 to 33 positive cores, and 4% had 34 or more positive cores. (Not all men had biopsies.)

No difference between assessments

No difference was seen between 3-month and 6-month assessments in subsets of low- and very low-risk patients, and no difference in disease progression was observed between assessments at these two time points. The lack of an observed difference was confirmed by a kernel density plot showing no difference in the slope of PSA between 3-month and 6-month measurements, as well as a Bangdiwala observer agreement chart showing no systematic difference in disease progression when using either 3-month or 6-month measurements.UT

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