25-Year Disease-Free Survival Rate After Irradiation for Prostate Cancer Calculated with the Prostate Specific Antigen Definition of Recurrence Used for Radical Prostatectomy

Purpose: We addressed whether there is durable control of prostate cancer, defined as a prostate specific antigen cutoff of less than 0.2 ng/ml, greater than 20 years after irradiation for this disease. We also evaluated late recurrence, defined as recurrence after 10-year followup. Materials and Methods: A total of 3,546 consecutive hormone naive men were treated with a I-125 prostate implant (retropubic and later transperineal), followed by external beam irradiation, from 1984 to 2000. Recurrence was defined as a prostate specific antigen increase of greater than 0.20 ng/ml or a prostate specific antigen nadir of greater than 0.20 ng/ml. Median followup was 11 years (range 3 months to 26 years). Results: In all men 10, 15, 20 and 25-year disease-free survival rates were 75%, 73%, 73% and 73%, respectively. Longest time to recurrence was at the 15.5-year followup. In 313 men with recurrence who were treated 16 to 25 years ago 5% of recurrences were late. In men implanted by the transperineal method since 1995 the 15-year disease-free survival rate was 79%. Conclusions: With this irradiation program cancer control, defined using the recurrence definition for radical prostatectomy, was durable with no further recurrence between 15.5 and 25 years of followup. This study also suggests that at least 15 years of followup are necessary to fully evaluate any prostate cancer treatment. Furthermore, if prostate specific antigen is less than 0.20 ng/ml 15 years after treatment, later recurrence should be unlikely.