First Study to Evaluate 25 Years of Compiled Data After Radiotherapy for Prostate Cancer

The study, conducted by four physicians from Radiotherapy Clinics of Georgia (RCOG), a Vantage Oncology affiliate, and is called 25 Year Disease-Free Survival Rate after Irradiation of Prostate Cancer Calculated with the Prostate-Specific Antigen [PSA] Definition of Recurrence Used for Radical Prostatectomy. The study’s findings were published in the March 2013 issue of the Journal of Urology, the official journal of The American Urological Association.

Frank Critz, MD, founder and medical director at RCOG, the largest US community-based prostate program, cowrote this study along with three other RCOG physicians, James Benton, MD, Philip Shrake, MD, and Mark Merlin, MD. The prostate program at RCOG is the only program of its kind to have gathered and maintained a clinical records database for all patients over a 30-year period in a consistent and comprehensive manner. “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, late recurrence will be rare.”

This research study included 3,546 hormone naïve men with prostate cancer treated by I-125 implant followed by external beam radiation. 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 this irradiation program.

To compare similar populations, this study compares patients treated between 1984-2000 to two previous prostatectomy studies, which analyze 15 years of follow-up information and a disease-free survival (DFS) calculation with a PSA < 0.2. The surgical definition is much narrower than the one typically used in radiation therapy studies. Results showed comparable DFS at 10 (75%, 77%, 77%) and 15 years of follow-up (73%, 68%, 75%). A sub-analysis of patients treated with transperineal implants between 1995 and 2000 showed a 15-year disease-free survival (DFS) of 79%.

The analysis includes over 300 men whose prostate cancer recurred who were treated 16-25 years ago. Recurrences were PSA defined and results demonstrated that most recurrences occurred within the first five years after treatment and no recurrences were noted 15.5–25 years after treatment.

This study concluded that follow-up evaluations are essential for 15 years after treatment to completely understand the outcomes of any treatment for prostate cancer. Unlike an earlier study with patients recurring after prostatectomy, this is the first to include interval-censoring analysis when looking at time to recurrence. If a man’s PSA is < 0.20 ng/mL 15 years post-treatment, later recurrence of the disease should be rare.

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Radiotherapy Clinics of Georgia