Penile erectile function after permanent radioactive seed implantation fortreatment of prostate cancer

Purpose: We assess erectile function after prostate brachytherapy and analy ze those factors affecting potency preservation. Materials and Methods: A total of 416 patients treated from October 1990 to September 1998 with permanent radioactive seed implantation for T1 to T2 p rostate cancer had erectile function assessed before and after treatment. E rectile function was assessed using the scoring system of 0-complete inabil ity to have erections, 1-able to have erections but insufficient for interc ourse, 2-can have erections sufficient for intercourse but considered subop timal and 3-has normal erectile function. Implant dose was defined as the D 90, which was the dose delivered to 90% of the gland on a dose volume histo gram from the 1-month computerized tomography based dosimetric analysis. Results: Pretreatment erectile function assessment revealed scores of 0 in 57 (14%), 1 in 46 (11%), 2 in 77 (18%) and 3 in 236 (57%) patients. In 313 patients who were potent with a score 2 or greater before therapy the actua rial freedom from any decrease in erectile function score was 64% and 30% a t 3 and 6 years, respectively. The actuarial preservation of potency, with a score 2 or greater, was 79% and 59% at 3 and 6 years, respectively. The 2 factors found to have a significant negative effect on potency in univaria te and multivariate analyses were high implant dose (D90 greater than 160 G y. for I-125 and D90 greater than 100 Gy. for Pd-103) and a pretreatment er ectile function score of 2 versus 3. Conclusions: The rate of potency preservation after brachytherapy is high, although a decrease occurs from 3 to 6 years. Pretreatment erectile dysfunc tion as well as higher implant dose are associated with greater impotency.