PSA-based triggers for treatment in active surveillance protocols
Posted Oct 12 2010 12:00am
A new report from Laurence Klotz’s group in Toronto basically tells us that no currently identified PSA-based “trigger” can be used alone to determine when a man on active surveillance should be switched over to active treatment.
This new paper by Loblaw et al. , due to appear in the November issue of the Journal of Urology, but already available on-line, provides data from a prospective, Phase II clinical trial including data from 450 patients on active surveillance. Of these patients, 315 had received no treatment for their prostate cancer at the time of the current analysis (April 2009), and 305 of these 315 patients were eligible for data analysis.
In this cohort of 305 patients, Loblaw et al. tested nine different PSA-based triggers in three groups for their potential to predict the value of treatment:
PSA threshold triggers
PSA doubling time triggers
PSA velocity triggers
The precise means of calculating the various PSA doubling time and PSA velocity triggers are described in the full text of the paper.
Of the 305 patients whose data was analyzed, it is important to understand that at a median follow-up of 6.1 years (in addition to the fact that not one has ever received active treatment for their prostate cancer), none have had any indication of metastatic disease and none have died of prostate cancer. Despite this fact:
All the abovementioned triggers would have recommended treatment for at least a percentage of these patients.
The range recommended for treatment was between 13.5 and 84.3 percent.
The absolute PSA value of > 20 ng/ml recommended treatment in only 13.5 percent of patients.
The selected PSA velocity > 2 ng/ml/yr recommended treatment in 84.3 percent of patients
In the conclusion to this paper, Loblaw et al. write as follows:
A transient increase in PSA should be interpreted with caution in men on active surveillance. If active surveillance is to be an effective long-term [management] option for men with favorable risk prostate cancer, more work is needed to identify a trigger which better strikes the balance between recommending treatment for those at high risk for progression and minimizing treatment for those at low risk for progression.
It should also be noted that of the 450 patients originally entered into the active surveillance protocol by Klotz and his colleagues, 117 (26 percent) were reclassified as having higher risk after initial entry into this study and subsequently received treatment, as reported by Klotz et al. in a publication earlier this year .
The “classic” reason for switching a patient from active surveillance to active treatment is an increase in the patient’s Gleason score (usually from 6 to 7 or higher) on follow-up biopsy.