Testosterone Profiles After Brachytherapy for Localized Prostate Cancer

Abstract Objective To evaluate patients’ serum total testosterone levels (STLs) after brachytherapy (BT) for prostate cancer. Methods We enrolled 102 men who underwent permanent interstitial BT using I 125 without androgen deprivation therapy for localized prostate cancer. Seed BT radiation dose was 145 Gy. Patients were followed for 24-60 months after BT. The primary outcome was STL kinetics after BT. Predictors of testosterone decrease were also analyzed. Results Median preimplantation STL was 4.18 ng/mL. STL decreased significantly to a median nadir of 89.4% of baseline (3.72 ng/mL) occurring at 6 months, and then recovered to baseline at 18 months after BT. The group of patients whose STLs fell below 3.00 ng/mL (biochemical hypogonadism) after BT started with lower baseline STLs (median: 3.54 ng/mL) than patients whose STLs did not fall below 3.00 ng/mL (median: 4.90 ng/mL). The group of patients whose STLs decreased by more than 1.00 ng/mL over the study period had significantly higher median baseline STLs (median: 5.05 ng/mL) than the group whose STLs decreased by less than 1.00 ng/mL (median: 3.64 ng/mL). Conclusion Although STL decreased significantly after I 125 -based BT, STL decline after treatment for localized prostate cancer was not large and recovered over time.