Prostate specific antigen: a prognostic marker of survival in good prognosis metastatic prostate cancer? (EORTC 30892).

Abstract

We study the value of PSA response and PSA progression as prognostic factors for survival in good prognosis metastatic prostate cancer. Data from 257 patients treated with Flutamide or Cyproterone acetate within the EORTC GU Group protocol 30892 have been used and analysis by Cox models. A PSA response defined as a decrease to < or = 1 ng/ml and to between 1 and 10 ng/ml was associated with a hazard ratio of 0.30 and 0.61 for overall survival, respectively, as compared to the non-responders (PSA> 10 ng/ml). Five definitions of PSA progression were considered: (1) a confirmed or (2) a repeated doubling of the PSA over nadir and unconfirmed (3) 100%, (4) 50% and (5) 20% increase of the PSA over nadir, each to a value > 4 ng/ml. Definition (5) was the most sensitive with sensitivity 76.20% and specificity 32.08%. With this definition, 70.0% of the patients had a PSA progression, which occurred in median 1.98 years before death. For good prognosis metastatic prostate cancer patients under anti-androgen treatment, PSA response at 6 months with cut-off levels of < or = 1 ng/ml and < or = 10 ng/ml is prognostic for survival. A 20% increase over nadir to a value > 4 ng/ml is prognostic for a poor survival with a 76.20% sensitivity. In this study, confirmation of the increase by a second observation did not seem necessary. Genuine surrogacy is not established in this study.