Post-RT PCa recurrence unlikely after 15 years

March 4, 2013

Nearly three-quarters of patients undergoing radiation therapy for prostate cancer had no evidence of the disease at 25 years’ follow-up, the authors of a study from Radiotherapy Clinics of Georgia, Atlanta recently reported.

Nearly three-quarters of patients undergoing radiation therapy for prostate cancer had no evidence of the disease at 25 years’ follow-up, the authors of a study from Radiotherapy Clinics of Georgia, Atlanta recently reported.

"This study, the longest after irradiation of prostate cancer, confirms, using the surgical PSA definition (PSA <0.2 ng/mL), that results from this program are equal to that of radical prostatectomy, thus giving men a choice of treatment, and after 15-year follow-up, if the PSA is <0.2 ng/mL, late recurrence will be rare," said the authors, led by Frank A. Critz, MD.

The study, which was published in the Journal of Urology (2013; 189:878-83), included 3,546 hormone-naïve men with prostate cancer treated by I-125 implant followed by external beam radiation therapy. The initial cohort was treated with retropubic implants, and as technology improved, the implant technique was changed to a transperineal template/ultrasound-guided approach, which was the technique used in 2,875 of these men.

Seventy-three percent of men had no evidence of prostate cancer 25 years after treatment. To compare like populations, the authors compared patients treated between 1984 and 2000 to two previous prostatectomy studies that analyzed 15 years of follow-up data and a disease-free survival (DFS) calculation with a PSA <0.2 ng/mL. The surgical definition is much stricter than the one usually used in radiation therapy studies, researchers say.

Results showed comparable DFS at 10 years of follow-up, with 75%, 77%, and 77% DFS rates for the radiation and prostatectomy series respectively. Fifteen-year follow-up also yielded comparable DFS rates of 73%, 68%, and 75%, respectively. A sub-analysis of patients treated with transperineal implants between 1995 and 2000 showed a 15-year DFS of 79%.

The analysis included over 300 men whose prostate cancer recurred who were treated 16 to 25 years ago. Recurrences were PSA defined, and results showed the majority of recurrences occurred within the first 5 years after treatment, and no recurrences were noted 15.5 to 25 years after treatment.

The authors concluded that evaluations are necessary for 15 years after treatment to fully understand the outcomes of any treatment for prostate cancer. If a man's PSA is <0.20 ng/mL 15 years post treatment, later recurrence of the disease should be rare, they said.

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