Pretreatment Nomogram Predicting Ten-Year Biochemical Outcome of Three-Dimensional Conformal Radiotherapy and Intensity-Modulated Radiotherapy for Prostate Cancer

Abstract

To update our previously published nomogram predicting for biochemical outcome with 10-year data from a larger cohort of patients treated with three-dimensional conformal radiotherapy (RT) or intensity-modulated RT for localized prostate cancer. From 1988 to 2004, 2253 patients were treated with three-dimensional conformal RT or intensity-modulated RT for clinical Stage T1-T3 prostate cancer. Prescription doses ranged from 64.8 to 86.4 Gy. The median follow-up time was 7 years. The nomogram was developed using a proportional hazards regression model predicting for the probability of biochemical relapse after RT according to the nadir plus 2 ng/mL definition of prostate-specific antigen (PSA) relapse. The 10-year PSA relapse-free survival rate was 62%. The nomogram incorporated the following variables to predict likelihood of PSA failure after RT: pretreatment PSA level, Gleason score, radiation dose, use of neoadjuvant androgen deprivation, and clinical stage. The concordance index of this long-term nomogram was 0.72. A nomogram predicting the 10-year probability of biochemical control after three-dimensional conformal RT or intensity-modulated RT for prostate cancer was reasonably accurate and discriminating. The nomogram also provided evidence that long-term biochemical control can be achieved after conformal RT for the treatment of localized prostate cancer.