Time to PSA detection after surgery predicts prostate cancer recurrence
MedWire News: The risk for possible disease recurrence indicated by biochemical failure after surgery for prostate cancer decreases the longer it takes to detect a patient's prostate-specific antigen (PSA) level, study findings show.
US researchers examined the need for rigorous PSA surveillance after radical prostatectomy (RP), and found that biochemical failure in the year after an undetectable PSA level is uncommon among low-risk patients, especially after a PSA-free period of 3 years.
"Despite the fact that the likelihood of cancer recurrence decreases with increasing time after surgery, many low risk patients continue to be followed at frequent intervals," say Matthew Tollefson and colleagues from the Mayo Clinic in Rochester, Minnesota.
"Aggressive postoperative PSA surveillance is costly for societies and anxiety provoking for patients," they add, in the Journal of Urology.
The study cohort included 2219 RP patients with low-risk disease, defined as having a preoperative PSA level of less than 10 ng/ml, stage T2c disease or less, a Gleason score of 6 or less, negative pelvic lymph nodes, negative surgical margins, and no neoadjuvant hormone or radiation therapy.
Biochemical failure was defined as a single postoperative PSA measurement of 0.4 ng/ml or greater taken during post-RP follow-up, which lasted a median of 75 months and consisted of PSA testing every 3 months for the first year, every 6 months for the second year, and annually thereafter.
In all, 142 (6.4%) patients experienced biochemical failure, and a further 200 (9.0%) had a detectable PSA without reaching the 0.4 ng/ml threshold for failure.
For each year of undetectable PSA (less than 0.15 ng/ml) the likelihood of recurrence decreased significantly. While 3.8% of patients who experienced undetectable PSAs during the first year after RP ultimately went on to experience recurrence, this decreased to 2.8%, 1.8%, 1.4%, and 1.4% for patients with undetectable PSA levels in the 2nd, 3rd, 4th, and 5th years after surgery, respectively.
The researchers evaluated the likelihood of recurrence within the year following the most recent PSA measurement, and report that after 1 year of undetectable PSAs, only 0.1% of patients recurred in the next year. After 3 years of undetectable PSAs, 0.2% of men progressed in the following year.
"These data suggest that annual PSA measurements are unnecessary, especially after a PSA-free interval of 3 years," conclude Tollefson et al.
Based on their findings, the team recommends that 2-yearly PSA measurements for low-risk patients would capture the majority who experience progression.
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By Sarah Guy