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Conflicting data exists regarding the effectiveness of continuous versus intermittent dosing strategies for patients with prostate cancer. In a Canadian study that examined patients with prostate cancer who had a rising PSA or were PSA recurrent, intermittent androgen deprivation therapy (ADT) was found to be noninferior to the continuous dosing strategy, suggests David I. Quinn, MD.
For this small subset of patients, an intermittent strategy may be efficacious; however, these patients may also be suitable for active surveillance, Quinn believes. Intermittent ADT may also be ideal for patients with a PSA doubling time of less than 3 months, since metastases are likely to develop within 12 months.
In a SWOG study, patients who responded to ADT were randomized to intermittent or continuous therapy. In this trial, intermittent therapy was shown to be inferior to continuous. In fact, Quinn points out, the median overall survival with intermittent therapy was 18 months less than with continuous dosing. However, quality of life with intermittent ADT was better than continuous.
These results warrant an open discussion with each patient to determine an individualized approach. However, E. David Crawford, MD, adds, the quality of life gains with the intermittent approach were not substantial.