A standard definition of disease freedom is needed for prostate cancer: Undetectable prostate specific antigen compared with the American Society of Therapeutic Radiology and Oncology Consensus Definition

Purpose: Freedom from prostate cancer is defined by undetectable prostate specific antigen (PSA) after surgery and the American Society of Therapeutic Radiology and Oncology (ASTRO) criteria are recommended for irradiation. Whether these definitions of disease freedom are comparable was evaluated in this study. Materials and Methods: From August 1992 to August 1996 simultaneous irradiation with prostate 125 iodine implantation followed by external beam irradiation was performed in 591 consecutive men with stage T1T2NX prostate cancer. All patients had a transperineal implant and none received neoadjuvant hormones. Disease freedom was defined by a PSA cutoff of 0.2 ng./ml. and the ASTRO consensus definition. Median followup was 6 years (range 5 to 8). Results: Of the 591 men in this study 65 had recurrence by ASTRO criteria and 93 had recurrence by a PSA cutoff of 0.2 ng./ml., which was a significant difference (p = 0.001). On multivariate analysis of the factors related to disease-free status the definition of disease freedom, pretreatment PSA and Gleason score were highly significant. Of the 528 men with a minimum 5-year PSA followup the 8-year disease-free survival rate by ASTRO criteria was 99% in those who achieved a PSA nadir of 0.2 ng./ml. and 16% in those with a nadir of 0.3 to 1 ng./ml. Of the 469 disease-free patients by ASTRO criteria with a minimum 5-year followup 455 (97%) achieved a PSA nadir of 0.2 ng./ml. or less. Conclusions: The definition of freedom from prostate cancer significantly affects treatment results. A standard definition is needed and a PSA cutoff of 0.2 ng./ml. is suggested as the standard for all curative treatments for localized prostate cancer.