10-YEAR DISEASE-FREE SURVIVAL RATES AFTER SIMULTANEOUS IRRADIATION FOR PROSTATE CANCER WITH A FOCUS ON CALCULATION METHODOLOGY

Abstract

We documented the 10-year disease-free survival rate after simultaneous irradiation for prostate cancer and suggested standards for outcome calculation methodology. From 1992 to 1998, 1,469 consecutive men with clinical stage T1T2NxM0 prostate cancer who did not receive neoadjuvant hormones were treated with simultaneous irradiation, an ultrasound guided transperineal prostate I seed implant followed by external irradiation. Median pretreatment prostate specific antigen (PSA) was 7.1 ng/ml (range 0.3 to 88). All men were treated 5 or more years ago. Median followup was 6 years (range 3 months to 11 years). Disease freedom was defined as the achievement and maintenance of PSA 0.2 ng/ml or less, and treatment failure was defined as a PSA nadir greater than 0.2 ng/ml or a subsequent PSA increase above this level. The overall 10-year disease-free survival rate was 83%. Median time to recurrence was 30 months (range 3 months to 8 years) and 24% of recurrences were after 5-year followup. The 10-year outcome according to low, intermediate and high risk group was 93%, 80% and 61%, respectively (p <0.0001). Multivariate analysis of factors related to disease freedom documents that pretreatment PSA, Gleason score and percent positive biopsies were significant but stage and age were not. By calculating outcome with PSA cut point 0.2 ng/ml and evaluation only of men treated 5 or more years ago, the 10-year disease-free survival rates from this study can be reasonably compared with the outcome of radical prostatectomy performed in the PSA era.