Patterns of failure after iodine-125 seed implantation for prostate cancer

Purpose: To determine the site of relapse when biochemical failure (BF) occurs after iodine-125 seed implantation for prostate cancer. Materials and methods: From 2001–2009, 500 men underwent implantation in Wellington, New Zealand. Men who sustained BF were placed on relapse guidelines that delayed restaging and intervention until the prostate-specific antigen (PSA) was ⩾20 ng/mL. Results: Most implants (86%) had a prostate D90 of ⩾90%, and multivariate analysis showed that this parameter was not a variable that affected the risk of BF. Of 21 BFs that occurred, the site of failure was discovered to be local in one case and distant in nine cases. Restaging failed to identify the site of relapse in two cases. In nine cases the trigger for restaging had not been reached. Conclusions: If post-implant dosimetry is generally within the optimal range, distant rather than local failure appears to be the main cause of BF. Hormone treatment is therefore the most commonly indicated secondary treatment intervention (STI). Delaying the start of STI prevents the unnecessary treatment of men who undergo PSA 'bounce' and have PSA dynamics initially mimicking those of BF