Accurate treatment triggers needed for prostate cancer patients on surveillance
MedWire News: The standard prostate-specific antigen (PSA) measurements used to evaluate low-risk prostate cancer patients on watchful waiting programs may result in many being unnecessarily triggered for active treatment, says a Canadian research team.
Andrew Loblaw and colleagues, from the University of Toronto in Ontario, believe that for watchful waiting to be an effective long-term management option for favorable risk prostate cancer, "the number of patients in whom an inappropriate PSA trigger results in definitive treatment should be minimized."
The team determined the proportion and frequency of patients with nonprogressive disease who would have had a treatment trigger based on meeting a PSA threshold for treatment (>10 ng/ml or >20 ng/ml), having a high PSA velocity (>2 ng/ml per year), or fast PSA doubling time (<2 years).
The cohort included 305 men with stage T1b-T2b N0Mo disease, a Gleason sum of 7 or less, and a PSA of 15 ng/ml or less. The median follow-up was 6.1 years, during which time none of these patients had treatment or evidence of distant metastases, and none died of prostate cancer. Nevertheless, between 13% and 86% of men met the PSA trigger criteria for active treatment, depending on the definition used.
The more conservative PSA threshold of 10 ng/ml, would have triggered treatment in 38% of the 265 men whose baseline PSA was under the threshold for treatment. In comparison, a PSA threshold of 20 ng/ml or less would have triggered treatment in only 13.5% of patients.
PSA velocity indicated the greatest number of possible treatment triggers. Using successive, and overall PSA measurements, a respective 84.3% and 42.3% of patients had a PSA velocity of 2 ng/ml per year at least once during follow-up and based on this would have been actively treated.
PSA doubling times resulted in 37.4-49.8% of patients qualifying for active treatment, depending on whether all available PSA measurements or just first-last PSA measurements were used. However, Loblaw et al believe doubling time is too cumbersome to be calculated in busy clinics.
"More work is needed to identify a trigger which better strikes the balance between recommending treatment for patients at high risk for progression, and minimizes treatment for those at low risk for progression," conclude the researchers in the Journal of Urology.
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By Sarah Guy