What defines therapeutic benefit for patients with recurrent prostate cancer ? reducing PSA, delaying clinical progression or cancer specific survival? As new treatments advance through clinical trials urologists are faced with interpreting new definitions of efficacy. In this study of men with PSA only recurrence after radical prostatectomy GVAX vaccination resulted in modest PSA decreases in 8 of 19 patients and a median time to PSA progression of 10 months. However, PSA progression is defined as a 50% increase above a nadir. While this measure has been used in other trials I am uncertain how this became an accepted criterion. It appears to me to be a hollow, misleading term, implying PSA stabilization while in reality the PSA continues to increase, hardly a lack of progression. I have reservations about continuing the use of this definition to perpetuate a seemingly invalid measure in the literature. Vaccination did influence PSA kinetics, increasing the mean PSA doubling time from 28.7 weeks before treatment to 57.1 weeks after treatment. It is clear that PSA velocity and doubling times are indicators of prognosis in patients with prostate cancer, but there are no data indicating that an intervention which impacts the rate of increase results in any impact on clinical progression or overall survival. Until we have such data we need to interpret these results accordingly and mute our overenthusiasm in interpreting the results without validation with conventional indicators of disease control. (Source: The Journal of Urology)
Original source: http://www.jurology.com/article/PIIS0022534708020533/abstract?rss=yes
