Effect of aging and long-term erectile function after iodine-125 prostate brachytherapy.

Abstract

To evaluate long-term erectile function (EF) in men treated with iodine-125 prostate brachytherapy (PB) and to determine factors predictive for erectile dysfunction (ED), including natural decline because of aging. Two thousand nine hundred twenty-nine patients (implanted July 1989-June 2012) with baseline EF and greater than 10-month followup (FU) are included. About 78.9% had full and 7.9% had partial EF at baseline. EF was assessed on a physician-reported three-point scale. Poisson regression with generalized estimating equations was used to assess predictors of ED and Kaplan-Meier curves time to ED. The effect of aging was calculated from the declining rate of baseline EF seen in sequential 5-year age cohorts and from the Massachusetts Male Aging Study. The median age was 66years and median FU 3.5years (maximum 14 years). About 1142 patients had more than 5years of FU, and 43% had received 6 months of androgen deprivation therapy (ADT). Significant drop in EF was seen at 6weeks after PB, with gradual decline thereafter. EF preservation at 5years for age younger than 55, 56-59, 60-64, 65-69, and 70year and older was 82%, 73%, 58%, 39%, and 23%, respectively. Comparisons of the 5-year age-related and treatment-related EF decline show that 50% of the long-term EF decline is related to aging. On univariate and multivariate analyses, age at implant, length of FU, hypertension, diabetes, and use of ADT (all p<0.01) were significant predictors of ED. More than 80% of young men have EF preserved 5years after PB. Age, ADT, history of hypertension, and the natural decline in EF have negative impact on long-term EF after PB.