INTERSTITIAL I-125 RADIATION WITHOUT ADJUVANT THERAPY IN THE TREATMENT OF CLINICALLY LOCALIZED PROSTATE CARCINOMA

BACKGROUND. This study was designed to evaluate the efficacy of iodine -125 interstitial radiation in the treatment of prostate carcinoma cla ssified as T1 or T2. METHODS. One hundred twenty-six consecutive patie nts with adenocarcinoma of the prostate (T1, 23%; T2, 77%) were treate d with iodine-125 radionuclides between January 1, 1988, and December 31, 1990. Four patients died of intercurrent illness within 1 year pos timplant, leaving 122 men in the study, The prescribed minimum radiati on dose was 160 gray. Median follow-up was 69.3 months. Prebiopsy pros tate specific antigen (PSA) values (median, 5.0 ng/mL) were available for all patients. Posttherapy evaluation included clinical, biochemica l (PSA), and pathologic (repeat needle biopsy) studies. No patient was surgically staged, and none received androgen deprivation therapy. Mo rbidity was graded according to the Radiation Therapy Oncology Group g rading scale. Statistical appraisal was performed by the Kaplan-Meier method. PSA failure was defined in two ways: (1) PSA progression, i.e. , 2 consecutive increases from a nadir value; and (2) failure to attai n an arbitrary serum PSA value of 1.0 or 0.5 ng/mL at last follow-up. RESULTS. The overall 7-year survival was 77%; there were no deaths fro m prostate carcinoma in this cohort. The 7-year actuarial PSA progress ion free outcome was 89%, and the PSA less than or equal to 1.0 ng/mL outcome was 87%. When PSA less than or equal to 0.5 ng/mL was selected as an outcome end point, and PSA values in this series of radiation-t reated patients were compared with PSA values proposed to indicate dis ease free survival after radical prostatectomy (PSA less than or equal to 0.3-less than or equal to 0.6 ng/mL), the 7-year actuarial disease free survival was 79%. Morbidity was minimal except in patients who h ad preimplant or postimplant transurethral prostate resection. CONCLUS IONS. Outpatient-based iodine-125 prostate brachytherapy for prostate carcinoma classified as T1 or T2 resulted in biochemical outcomes comp arable to end points resulting from radical prostatectomy and external beam radiation. (C) 1997 American Cancer Society.