PO69

Purpose Standard of care for localized prostate cancer is either surgical or radiotherapeutic. While total gland ablation was intended, recent efforts of certain institutions using cryotherapy or HIFU (High-Intensity Focused Ultrasound) have explored the efficacy of focal therapy for select patients. Diagnostic technology has evolved and improved the ability and accuracy to identify tumor extent and location. This analysis investigates low-dose-rate (LDR) focal prostate brachytherapy PSA outcomes by demonstrating impact and thus correlation with focal target volume. Method 132 patients, mean age 73.5 years old (range 48-89 y/o), underwent focal therapy using LDR prostate brachytherapy from 12/2007 - 2/2019. Patients were categorized as low (63/132, 47.7%), intermediate (55/132, 41.7%), or high (14/132, 10.6%) risk groups using D'Amico risk group stratification. Prescribed dose to focal target volume was 115Gy, 125Gy, 144Gy for Cs-131 (66/132, 50%), Pd-103 (1/132, 0.8%), and I-125 (65/132, 49.2%) respectively. Results Mean preplan focal target volume was 21.5cc (range 7.5-58.2cc). Mean planning total prostate volume was 63.1cc (range 18.1-143.1cc). Mean preplan focal target volume of the prostate, as a percentage of total prostate volume, was 30.6%. Median follow up was 20.2 months (range 1- 134 months). Focal brachytherapy greater than 1-year follow up, the PSA was impacted by a mean of 59.2% from initial PSA (95% Confidence Interval [58.7, 59.7]). Conclusion Focal LDR prostate brachytherapy may offer a more conservative therapeutic option for localized prostate cancer in select patients. For patients found to have recurrence of disease in the treated volume, or new disease identified in the untreated prostate volume, should be amenable to numerous salvage therapies. With further analysis, additional investigation will evaluate quality of life impact and dosimetric considerations. This analysis warrants further exploration of the role of LDR prostate brachytherapy treatment of select patients with localized prostate cancer. Standard of care for localized prostate cancer is either surgical or radiotherapeutic. While total gland ablation was intended, recent efforts of certain institutions using cryotherapy or HIFU (High-Intensity Focused Ultrasound) have explored the efficacy of focal therapy for select patients. Diagnostic technology has evolved and improved the ability and accuracy to identify tumor extent and location. This analysis investigates low-dose-rate (LDR) focal prostate brachytherapy PSA outcomes by demonstrating impact and thus correlation with focal target volume. 132 patients, mean age 73.5 years old (range 48-89 y/o), underwent focal therapy using LDR prostate brachytherapy from 12/2007 - 2/2019. Patients were categorized as low (63/132, 47.7%), intermediate (55/132, 41.7%), or high (14/132, 10.6%) risk groups using D'Amico risk group stratification. Prescribed dose to focal target volume was 115Gy, 125Gy, 144Gy for Cs-131 (66/132, 50%), Pd-103 (1/132, 0.8%), and I-125 (65/132, 49.2%) respectively. Mean preplan focal target volume was 21.5cc (range 7.5-58.2cc). Mean planning total prostate volume was 63.1cc (range 18.1-143.1cc). Mean preplan focal target volume of the prostate, as a percentage of total prostate volume, was 30.6%. Median follow up was 20.2 months (range 1- 134 months). Focal brachytherapy greater than 1-year follow up, the PSA was impacted by a mean of 59.2% from initial PSA (95% Confidence Interval [58.7, 59.7]). Focal LDR prostate brachytherapy may offer a more conservative therapeutic option for localized prostate cancer in select patients. For patients found to have recurrence of disease in the treated volume, or new disease identified in the untreated prostate volume, should be amenable to numerous salvage therapies. With further analysis, additional investigation will evaluate quality of life impact and dosimetric considerations. This analysis warrants further exploration of the role of LDR prostate brachytherapy treatment of select patients with localized prostate cancer.