Fifteen-year minimum follow-up of a prostate brachytherapy series: comparing the past with the present

To report the overall survival for 126 patients more than 15 years after iodine-125 interstitial therapy; to report the biochemical progression status for those alive and clinically without evidence of disease for longer than 15 years; to document the upward migration of grade by date of grade assignment; to compare the tumor stage and grade profile of this mature series with our current experience; and to clarify the prostate-specific antigen (PSA) data when this series is used as a historical comparison.

The records of 126 patients who underwent interstitial therapy more than 15 years previously were reviewed for assessment of the current TNM stage and Gleason grade and the current PSA level for patients clinically free of disease. The tumor grade and stage of these patients were compared with those of the first 126 patients treated by transrectal ultrasound-guided brachymonotherapy at our center between January 1995 and January 1999. The methodology of our 1993 publication was also reviewed.

Of the 16 patients clinically free of disease (13 still alive and 3 dead of other causes more than 15 years after therapy), a review of the initial diagnostic needle biopsy was unable to confirm the presence of tumor in 3 patients. Of the remaining 13, 4 had a PSA level of 0.2 ng/mL or less, 4 a PSA level between 0.21 and 0.9 ng/mL, and 5 a PSA level between 1 and 2.5 ng/mL. Re-evaluation of the histopathologic findings using current criteria increased the Gleason score and World Health Organization grade. Patients currently selected for brachytherapy have a lower Gleason grade and TNM stage than recorded for patients treated in the past. The actuarial progression probability curves using the 0.5 or less cutpoint published in 1993 represented the best possible outcome and cannot serve as a historical control for current series comparisons.

For patients who were alive and clinically free of disease longer than 15 years after therapy, the biochemical PSA levels were low. This may be attributed to the therapeutic radiation effect. Whether the improved technology of current transrectal ultrasound-guided implants can extend these favorable results from a small minority to a significant majority and whether it can approach the therapeutic results of radical prostatectomy may be partially answered with a longer follow-up of the current series. The histopathologic criteria have been refined, and upgrading from the initially assigned grade is common. In some cases, a prostate cancer diagnosis could not be confirmed. These findings limit the ability to match patients across time and institution. The results of our 1993 report of biochemical chemical progression-free probability 10 years after iodine-125 implantation cannot be used as a comparator for current studies. Ultimately, a valid comparison between treatment options will only be achieved through a randomized controlled trial.