Purpose: To assess the frequency and features of the PSA bounce phenomenon in a series of patients treated with permanent implant brachytherapy for prostate cancer, and to evaluate the percentage of cases in which this bounce could have mimicked a biochemical relapse according to the American Society for Therapeutic Radiology and Oncology consensus criteria.
Methods and materials: From January 1999 to December 2001, 295 patients were treated with a permanent prostate implantation (real-time technique, with free (125)I seeds) by the Paris Institut Curie/Hospital Cochin/Hospital Necker Paris group. Duration of followup is 40.3 months (9-66 months). PSA level was reported at intervals not exceeding 6 months. Bounce was defined by temporary elevation in PSA level, followed by a spontaneous decrease.
Results: In our series, 161 patients (55%) showed a transitory PSA increase (bounce) of at least 0.1 ng/mL; 145 patients (49%) a bounce of 0.2 ng/mL; 93 patients (32%) a bounce of 0.4 ng/mL; and 43 patients (15%) a bounce of at least 1 ng/mL. Mean PSA bounce was 0.8 ng/mL (0.1-4.1), and mean time to bounce was 19 months. Thirty-two patients (11% of total) presented three successive PSA increases, and therefore were to be considered as experiencing a biochemical relapse according to the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus criteria. Among those 32 patients, 18 (56%) subsequently showed, without any treatment, a complete normalization of their PSA. In multivariate analysis, age <70 (p<0.0001) and D90>200Gy (p<0.003) were identified as independent factors for a PSA bounce of at least 0.4 ng/mL.
Conclusions: The observed rate of 32% of patients showing a PSA bounce of at least 0.4 ng/mL in our series is in good agreement with what has been previously reported in the literature. Among 32 patients fulfilling the classical ASTRO criteria for a biochemical relapse, 18 (56%) subsequently showed a spontaneous PSA decrease, questioning the ASTRO consensus for the biochemical followup of patients undergoing permanent implant prostate brachytherapy.