Common PSA parameters are unsatisfactory treatment triggers during AS
MedWire News: Canadian research results show that current prostate-specific antigen (PSA) parameters used to monitor men under active surveillance (AS) for low-risk prostate cancer may result in an unacceptably high level of treatment intervention.
Despite being 19 times more likely to die of a cause other than prostate cancer, the researchers report that as many as 84% of AS patients in their study would have received active treatment on the basis of their PSA doubling times, velocity, or thresholds.
“These results show that a transient rise in PSA should be interpreted with caution in men on AS,” said Laurence Klotz (University of Toronto, Ontario) who presented his team’s results at the 2010 American Urology Association (AUA)’s annual meeting in San Francisco, California, USA, this week.
“Almost all of these commonly used PSA triggers would have resulted in high rates of recommendations for treatment, on repeated occasions,” he added.
Klotz and team prospectively compared three standard PSA triggers for radical treatment – two occurrences of PSA doubling, three separate increases in PSA velocity, or a PSA level of more than 10 or 20 ng/ml – in a group of 453 patients who all had favorable disease characteristics including stage T1b-T2b, a Gleason score less than 7, and a PSA of 15 ng/ml or less.
Men who had a PSA doubling time of 3 years or less, had grade progression on re-biopsy, or whose clinical nodule doubled in size during the median 6.8-year follow-up were offered radical treatment.
In all, 305 patients remained on AS without the offer of intervention and none died of prostate cancer or developed metastatic disease during follow-up. Their hazard ratio for the risk for dying of a cause other than prostate cancer was 18.6.
Of note, the proportion of patients who would have had a false trigger for intervention on the basis of a PSA threshold of 10 or 20 ng/ml was 38% and 14%, respectively, while 37–50% would have been offered treatment on the basis of their PSA doubling time, and 42–84% on the basis of their PSA velocity.
“There is a critical need for a trigger that strikes a balance between recommending treatment for patients at high risk for progression and minimizing treatment for those at low risk,” Klotz commented at the AUA meeting.
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By Sarah Guy