Three-dimensional stereotactic posterior ischiorectal space computerized tomography guided brachytherapy of prostate cancer: a preliminary report.

PURPOSE: A 3-dimensional (D) stereotactic posterior ischiorectal space computerized tomography (CT) guided approach is presented for brachytherapy of localized prostate adenocarcinoma. MATERIALS AND METHODS: During the last 2 years 130 patients 49 to 90 years old (median age 71) with clinical stage A, B or C adenocarcinoma have been treated by this method. The initial prostate specific antigen profile was range 0.9 to 143 ng./ml., mean, 16.25 and median 13.0. Range of initial prostatic volume was 30 to 156 cm.3, with a (median 62 and mean 65). Of the patients 15% had signs and symptoms of urinary obstruction, that is with residual urine greater than 100 cc and significant nocturia and frequency. Transurethral resection of the prostate defects were present in 20% of the patients. Volume and treatment planning is performed by CT. Placement of the after loading needles is accomplished with a 3-D stereotactic system mounted on a CT table. The prescribed dose is 12,000 cGy. for 103Palladium seeds and 16,000 for 125I. The dosage is achieved by spacing the after loading needles 10 mm. apart with the seeds averaging 10 mm. apart from center to center. RESULTS: Prostate specific antigen levels decreased to less than 2 ng./ml. in 95% of the patients including those at high risk 6 to 24 months after the procedure. Except for treatment related transient symptoms of urethritis and proctitis, there have been no complications. No patients had incontinence, acute infection, hemorrhage or radiation damage to the rectum. No patients required post-implant transurethral resection of the prostate. There was significant clinical improvement in patients with obstructive uropathy. CONCLUSIONS: The 3-D stereotactic CT guided posterior ischiorectal space approach for brachytherapy is not limited by prostate size, transurethral prostatic resection defects or public arch interference, and it allows for needle verification and correction if necessary. Initial clinical and biochemical results in patients treated with this method are promising.