Paul Schellhammer, MD

Dr. Roach initiates his discussion with the relevant statement that how we detect, stage, and treat carcinoma of the prostate, as well as subsequently evaluate treatment efficacy, has forever been dramatically altered by the availability of prostate specific antigen (PSA), which has been labeled "the most useful tumor marker available" [1]. However, as Dr. Roach also notes, new information and insights generate new questions and uncertainties about the best applications of this valuable tumor marker.