Purpose: To evaluate the effect of neoadjuvant androgen deprivation therapy on PSA kinetics following brachytherapy with or without supplemental external beam radiation therapy (XRT), to evaluate the magnitude and duration of the peak PSA, and to compare potential differences in PSA response curves between biochemically disease-free and failed patients.
Materials and methods: From November 1995 through August 2000, 179 consecutive patients with clinical T1b-T3a NxM0 (2002 AJCC) prostate cancer received neoadjuvant androgen deprivation therapy (median, 4 months) prior to brachytherapy using (103)Pd or (125)I with or without supplemental XRT. The median follow-up was 56 months. Following brachytherapy, PSA determinations were obtained at 3 months and then every 6 months thereafter. A median and mean of 9 and 9.5 PSA determinations, respectively, were obtained per patient. Biochemical disease-free survival was defined by the ASTRO and Houston definitions with both definitions used to determine the rate of overestimation of early biochemical failure secondary to testosterone recovery.
Results: Although a trend for higher baseline and peak PSA was noted in (125)I monotherapy patients, the difference between the 4 groups was not statistically significant (p = 0.088). Changes in PSA over time, however, were statistically significant (p = 0.042). For all 4 groups, the peak PSA occurred approximately 15-21 months following brachytherapy. For biochemically disease-free patients, the median PSA increase above nadir was 0.1 ng/mL, and the median number of consecutive rises in PSA was 1. Using the ASTRO and Houston definitions, only 2.3% and 0.6% of patients would have been inadvertently scored as failures.
Conclusions: In brachytherapy patients receiving 3-6 months of neoadjuvant androgen deprivation therapy, the median PSA increase above nadir was 0.1 ng/mL. The ASTRO and Houston definitions of biochemical failure inadvertently scored only 2.3% and 0.6% of patients as failures.