Relapse patterns after low-dose-rate prostate brachytherapy.

PURPOSE: When biochemical failure (BF) develops after low-dose-rate prostate brachytherapy, the relapse site is frequently not found. We set out to find whether prostate-specific membrane antigen positron emission tomography -CT (PSMA PET-CT) scanning has improved knowledge of relapse patterns. METHODS AND MATERIALS: A database was analyzed, which contained information and long-term followup on 903 men who had an iodine-125 seed implant as monotherapy for early-stage prostate cancer. There was a total of 68 BFs. RESULT: In 38 men developing BF before PSMA PET-CT scanning was available, the site of relapse was local in six, distant in twelve, and unknown in twenty. In 30 men developing BF more recently who had a PSMA PET-CT scan, the relapse site was demonstrated in all cases, and 19 (63%) men had relapsed at the prostate base. Radiation dosimetry of base relapses and paired controls demonstrated that implants routinely delivered a lower radiation dose to the base than to the rest of the prostate. Eight of seventeen cases found to have prostate relapse only underwent salvage prostatectomy. CONCLUSION: PSMA PET-CT scanning is highly effective in demonstrating the relapse site(s) when BF develops after low-dose-rate prostate brachytherapy. Knowledge of the relapse site increases management options for men developing BF.

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.

Parameters of perineural invasion in radical prostatectomy specimens lack prognostic significance.

The prognostic significance of perineural invasion by prostate cancer is debated. We have evaluated the association between biochemical failure and measurements of perineural invasion in radical prostatectomy specimens. Perineural invasion was identified in sections using S-100 protein immunostaining. For nerves showing invasion, the involved nerve closest to the edge of the prostate and to the surgical excision margin, as well as the diameter of these nerves, the largest nerve showing perineural invasion and its proximity to the excision margin, and the percentage of nerves showing perineural invasion up to 1.75 mm from the excision margin was determined and tested against time to prostate-specific antigen failure, along with preoperative prostate-specific antigen levels, highest Gleason primary grade, Gleason score and TNM T category. Perineural invasion was present in 90% of cases, with extraprostatic perineural invasion in 25% of tumors. Diameter of nerves showing perineural invasion ranged from 11 to 680 microm and the shortest distance to the surgical excision margin ranged from 33 to 2.57 mm. Perineural invasion density ranged from 6 to 96%. Gleason scores were six in 58 cases, seven in 43 cases, eight in three cases and nine in one case. Clinical T categories were T1c in 75 cases, T2a in 22 cases, T2b in five cases, T2c in two cases, T3 in one case. During a follow-up period of 11 to 55 months (median 26 months), 27 patients showed prostate-specific antigen failure. On univariate analysis only presence of extraprostatic perineural invasion, among parameters of perineural invasion, showed a weak correlation with outcome, while on multivariate analysis this lost significance and preoperative prostate-specific antigen levels, Gleason score and excision margin status were independently associated with biochemical failure. We conclude that the investigated parameters of perineural invasion do not predict prostate-specific antigen recurrence in radical prostatectomy specimens.