Biochemical outcomes and toxicities in young men with prostate cancer after permanent iodine-125 seed implantation: Prospective cohort study in 6662 patients

PURPOSE: We evaluated the effect of age, < 60 and >60 years, on biochemical outcomes and toxicities in patients with prostate cancer who underwent permanent seed implantation (PI) +/- external beam radiation therapy +/- hormone therapy in a national Japanese prospective cohort study (J-POPS). METHODS AND MATERIALS: The safety and efficacy analyses included 6721 and 6662 patients, respectively. We categorized patients into two age groups: < 60 ( n = 716) and >60 ( n = 6,005) years. We used propensity score matching (PSM) to estimate the marginal effect of age on biochemical freedom from failure (bFFF) using a Phoenix definition and Cox proportional hazard models. RESULTS: The median followup period was 60.0 months. Without PSM, men < 60 years demon-strated similar 5-year bFFF (96.3%) compared with men >60 years (95.6%; p = 0.576); percent positive biopsies, biologically effective dose, Gleason score, risk classification, and supplemental external beam radiation therapy ( p < 0.001, < 0.001, < 0.001, 0.008, and < 0.001) were signifi-cantly associated with bFFF while age was not ( p = 0.576). With PSM, bFFF was not significantly different between age groups ( p = 0.664); however, men < 60 years showed a significantly lower incidence of declining erectile function, grade >2 all urinary toxicities, urinary frequency/urgency, and rectal bleeding ( p < 0.001, 0.024, 0.031, and 0.010) than men >60 years. CONCLUSIONS: After PI, men < 60 years achieved a comparable 5-year biochemical control rate and showed a lower incidence of several toxicities compared to men >60 years. This suggests that PI should be an excellent treatment option for men < 60 years with prostate cancer. (c) 2022 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.