A Contemporary Report of Low-Dose-Rate Brachytherapy for Prostate Cancer Using MRI for Risk Stratification: Disease Outcomes and Patient-Reported Quality of Life †

SIMPLE SUMMARY: This study describes the outcomes of 149 men with prostate cancer treated at a single center with Iodine-125 low dose rate brachytherapy (also known as radioactive seed implant). A total of 98% of men were considered biochemically controlled 7 years after implant. Men without clear extra-prostatic extension of disease on MRI had very high rates of control, suggesting that MRI can be used to safely select men with “unfavorable intermediate risk” disease to be treated with an implant alone, rather than a combined course of external beam radiation with brachytherapy, as some guidelines recommend. Severe late side effects to the bladder and rectum were uncommon, and quality of life was well preserved, with mild changes in urinary and sexual health, particularly within the first 2 years after the implant. A table describing symptom distress over time is provided to help guide patient expectations regarding quality of life after brachytherapy. ABSTRACT: Purpose: We examined a prospective consecutive cohort of low dose rate (LDR) brachytherapy for prostate cancer to evaluate the efficacy of monotherapy for unfavorable-intermediate risk (UIR) disease, and explore factors associated with toxicity and quality of life (QOL). Methods: 149 men with prostate cancer, including 114 staged with MRI, received Iodine-125 brachytherapy alone (144–145 Gy) or following external beam radiation therapy (110 Gy; EBRT). Patient-reported QOL was assessed by the Expanded Prostate Index Composite (EPIC) survey, and genitourinary (GU) and gastrointestinal (GI) toxicity were prospectively recorded (CTC v4.0). Global QOL scores were assessed for decline greater than the minimum clinically important difference (MCID). Univariate analysis (UVA) was performed, with 30-day post-implant dosimetry covariates stratified into quartiles. Median follow-up was 63 mo. Results: Men with NCCN low (n = 42) or favorable-intermediate risk (n = 37) disease were treated with brachytherapy alone, while most with high-risk disease had combined EBRT (n = 17 of 18). Men with UIR disease (n = 52) were selected for monotherapy (n = 42) based on clinical factors and MRI findings. Freedom from biochemical failure-7 yr was 98%. Of 37 men with MRI treated with monotherapy for UIR disease, all 36 men without extraprostatic extension were controlled. Late Grade 2+/3+ toxicity occurred in 55/3% for GU and 8/2% for GI, respectively. Fifty men were sexually active at baseline and had 2 yr sexual data; 37 (74%) remained active at 2 yr. Global scores for urinary incontinence (UC), urinary irritation/obstruction (UIO), bowel function, and sexual function (SF) showed decreases greater than the MCID (p < 0.05) in UC at 2 mo, UIO at 2 and 6 mo, and SF at 2–24 mo, and >5 yr. Analysis did not reveal any significant associations with any examined rectal or urethral dosimetry for late toxicity or QOL. Conclusion: Disease outcomes and patient-reported QOL support LDR brachytherapy, including monotherapy for UIR disease.