Prostate brachytherapy: treatment strategies.

PURPOSE: Patients who present with localized and locally advanced prostate cancer may be candidates for prostate brachytherapy. We evaluated the treatment outcomes in a diverse group of prostate cancer patients who presented with low, moderate and high risk features.

MATERIALS AND METHODS: A total of 301 patients who presented with T1 to T3 prostate cancer were treated with brachytherapy alone or combined with hormonal therapy and/or external beam irradiation. Of these patients 109 at low risk with prostate specific antigen (PSA) 10 ng./ml. or less, Gleason score 6 or less and clinical stage T2a or less were treated with 125iodine alone, 152 at moderate risk with PSA greater than 10 ng./ml., Gleason score greater than 6 or stage T2b or greater were treated with 125iodine or 103palladium or combined implant alone with 5 months of hormonal therapy, and 40 at high risk with PSA greater than 15 ng./ml., Gleason 8 or greater, clinical stage T2c to T3 or positive seminal vesicle biopsy (20) were treated with combination brachytherapy, external beam irradiation and 9 months of hormonal therapy. Patients with a positive seminal vesicle biopsy (T3c disease) and negative pelvic lymph nodes were included in the high risk group, and the walls of the seminal vesicles were also treated with implantation. Followup was performed every 6 months with digital rectal examination and ultrasound evaluation. Prostate biopsy was routinely recommended 2 years after completion of the radiation. Failure was defined as PSA increase on 2 consecutive determinations above 1 ng./ml. or evidence of local recurrence on digital rectal examination, transrectal ultrasound or biopsy. Kaplan-Meier projections were used to calculate progression-free survival rates.

RESULTS: Of the 109 patients at low risk followed from 1 to 7 years (median 18 months) 91% were free of PSA failure at 4 years. No patient experienced urinary incontinence following implantation, although grade 1 to 2 radiation proctitis occurred in 5 (4.5%). Of the 152 patients at moderate risk 73 received implantation and 79 received implantation combined with hormonal therapy. The 4-year biochemical freedom from failure rate for the hormone group was 85% versus 58% for the no hormone group (p = 0.08). The difference was more significant for those with Gleason score 7 or greater (90 versus 43%, p = 0.01) and for those with PSA greater than 10 ng./ml. (87 versus 59%, p = 0.04). Grade 1 to 2 radiation proctitis occurred in 1 of the 79 patients (1.3%) receiving hormonal therapy and in 3 (4%) treated with implantation only. There were no cases of urinary incontinence. Of the 40 patients at high risk 71% were free of biochemical failure at 3 years. Of the 4 patients with failure (10%) 3 (75%) originally had positive seminal vesicle biopsies. Five patients experienced gastrointestinal complications, although none was grade 3 or 4. The actuarial freedom from grade 2 proctitis was 82%. No patient experienced urinary incontinence. Prostate biopsies were negative in 87% of the low risk, 96.8 (hormone group) versus 68.6% (no hormone group) of the moderate risk (p = 0.0023) and 86% of the high risk patients.

CONCLUSIONS: Brachytherapy appears to offer comparable results to external beam irradiation and radical prostatectomy when patients are stratified by disease extent. Adopting a strategy of implant alone, implant with hormonal therapy or implant with hormonal therapy and external beam irradiation in patients who present with low to high risk features can improve the overall results in the more advanced cases.