Transurethral ¹³⁷Cs Medium Dose Rate Radiotherapy as a Boost for Small-Sized Localized Prostatic Carcinomas

Abstract

The aim of this study is to present preliminary experience with ¹³⁷Cs medium dose rate (MDR) afterloading transurethral radiotherapy for small-sized ( < 2.5 cm) prostatic carcinomas. The phase II protocol comprises 46 Gy of external beam radiotherapy, followed by two insertions (1 week apart) of 137Cs MDR transurethral brachytherapy, each one delivering 8 Gy to a point 0.5 cm from the urethral walls. The treatment is completed with a 14-Gy boost to the prostatic area through lateral external beam fields. Up to now, 9 patients have been treated. The transurethral insertion is a simple procedure, requires no anesthesia and the ultrasonographic observation precisely and easily guided the positioning of the applicator. All 9 patients are alive and disease-free 12-––36 months after the end of radiotherapy. One of them presented a mild degree of urethral stricture and none developed chronic proctitis or cystitis. Seven patients were sexually potent before radiotherapy and all of them maintained their potency. Transurethral radiotherapy for prostatic carcinoma requires further investigation. The radiation dose that the procedure delivers to the prostate is higher than the one prescribed for external beam irradiation regimens. Rectal and bladder dose is substantially reduced. Although the prostatic urethra receives a higher dose, the incidence of urethral stricture is low probably because of the small tissue volume (8 cm³) in the high radiation dose area.

High Dose Rate Transurethral Brachytherapy as a Boost Dose for Localized Adenocarcinoma of the Prostate

“…Golby and Rowland [13] per formed afterloading LDR l37Cs and HDR l92Ir treatment in stage A patients. Skarlatos et al [14] reported their experience with medium dose rate l37Cs.…”