PROSTATE-SPECIFIC ANTIGEN AFTER RADIATION-THERAPY - PROGNOSIS BY PRETREATMENT LEVEL AND POSTTREATMENT NADIR

After external beam radiation therapy, pretreatment prostate-specific antigen (PSA) is the most powerful predictor of outcome as measured PS A (biochemical) failure. The post-treatment nadir levels of PSA that p redict best for subsequent freedom from PSA failure are debatable, and many nadir levels have been proposed as targets. Although lower nadir s generally are associated with superior outcomes, the identification of a single absolute nadir level was not selected at a recent ASTRO co nsensus conference. Rather, three consecutive PSA rises above the nadi r, with date of failure at the midpoint between the nadir and first ri se, were selected as a more useful end point for treatment failure.