Medium-term oncological and functional outcomes of hemi-gland brachytherapy using iodine-125 seeds for intermediate-risk unilateral prostate cancer

Abstract PURPOSE To examine medium-term outcomes of hemi-gland low-dose-rate brachytherapy as a primary treatment for intermediate-risk prostate cancer. METHODS We recruited intermediate-risk unilateral prostate cancer patients for a prospective trial of hemi-gland brachytherapy. Twenty-four patients underwent hemi-gland iodine-125 seed implantation with a prescribed dose of 160 Gy. Serum prostate-specific antigen (PSA) was measured regularly and follow-up biopsy was scheduled after 2–3 years of treatment. When clinically needed afterward, for-cause biopsy was performed to confirm pathology. Treatment failure (TF)-free survival, which was defined as freedom from radical or systemic therapy, metastases, and cancer-specific mortality, was assessed, as was biochemical failure (BF)-free survival. Urinary and sexual functions were also evaluated. RESULTS Median follow-up duration was 61 months. Twenty-two patients (92%) exhibited a declining trend or decreased value of PSA for 12 months or longer after the treatment. Follow-up biopsy in the initial triennium and for-cause biopsy in the subsequent triennium were performed in 16 and four patients, respectively, and cancer was found from the treated lobe in one patient (4% of the cohort) and significant cancer was found from untreated lobes in four patients (17%) in total. Secondary treatments were performed in six patients successfully. Five-year freedom from BF, TF, and metastasis was 71%, 90%, and 100%, respectively. The International Prostate Symptom Score significantly deteriorated at 3 months and reversed itself afterward. The International Index of Erectile Function 5 had no significant decrease. CONCLUSIONS Hemi-gland low-dose-rate brachytherapy provides favorable medium-term oncological outcomes with genito-urinary functional preservation for men with intermediate-risk unilateral prostate cancer.