INTRODUCTION

Radioterapia Botafogo is prepared to perform BRACHYTHERAPY with implantation of "seeds"of iodine-125 implantation, the latest technique in the treatment of early carcinoma of the prostate. The word "seeds" is a reference to the size and shape of the radioactive sources, which measure 5 mm long and 0.5 mm thick, resembling a rice seed.
This method, recently developed in Seattle, Washington, has been subject to increasing international approval, thanks to its high rate of local control of the disease, and to the preservation of urinary continence and of sexual potency in most cases.

METHOD

Procedure consists of implanting several I-125 seeds into the prostate, by means of special needles introduced through the perineum under spinal anesthesia, guided by direct viewing of the transrectal ultrasonography.

Brachytherapy of the prostate may be performed in isolation or associated with conventional external radiotherapy.
There must be a strict selection of candidates for isolated brachytherapy. Its indication should be limited to cases where clinical examinations, laboratory tests and radiological exams show an early stage of the disease, still confined within the prostatic capsule ( Stage T1B - T1C, T2A- T2B - T2C, NO, MO ).
If, however, focuses of neoplasic invasion are identified in prostate peripheral tissues, seminal vesicles or pelvic lymphnodes, a combination of brachytherapy and conventional external radiotherapy should be used in order to completely destroy the focuses and thus achieve the biochemical control of the disease.
The technique utilized by Radioterapia Botafogo is similar to the one used at Northwest Hospital in Seattle. At first, a volume study of the prostate is undertaken with transrectal ultrasonography, photographing the images from the base to the apex in axial plans. The contours of the gland, the exact position of the urethra and a possible interference of pelvic bones during the implant procedure is also evaluated. Those images are then transferred to a computer which, loaded with software specially developed for this technique, will determine the ideal number of seeds and the perfect positioning of the radioactive sources in the organ, for each specific case. Previous planning of the positioning for each I-125 seed is essential to obtain a high dose of radiation with uniform distribution throughout the treatment volume, eventually destroying all cancerous cells present.

ADVANTAGES OF BRACHYTHERAPY

Brachytherapy of the prostate with I-125 has been disseminating very fast not only due to its high rate of local control of the disease as well as to the low intensity of its side effects as compared to those of radical prostatectomy and external radiotherapy. The computer program also provides a map of the ideal distribution of the seeds, which implanted at previously well defined positions in the gland, will concentrate a high dose of radiation homogeneously distributed inside the prostatic capsule.
One of the main advantages of this method lies in the abrupt reduction of the dose-levels delivered to organs and the peripheral tissues, avoiding unnecessary radiation to the adjacent bladder and rectum, resulting in low-intensity temporary side effects, easily controlled by specific palliative medication. Therefore morbidity rate is lower than that of traditional surgical and radiotherapeutic methods.
Another advantage of brachytherapy with I-125 seeds is the short period required for hospitalization: only 24 hours are necesssary before discharge from hospital, carrying no risk of complications. Quick patient recovery after implantation should also be considered: four or five days later, patients can resume their social and professional activities, only avoiding great physical efforts during the following two weeks.

RESULTS

Although the analysis of this technique still requires a longer follow-up period, preliminary results of the biochemical control of the disease are similar to those achieved by radical prostectomy and slightly better than those obtained with conventional external radiotherapy. The Northwest Pacific Hospital in Seattle, an internationally recognized as the most experienced center in this field, published results after 7 years of follow-up, showing a prevalence of local control in 97% of the cases treated with exclusive brachytherapy and a local control of 87% in more advanced cases which received comBination external radiotherapy.
The rate of complications requiring minor surgical procedures such as uretral distension and cystoscopy was 8 %. More aggressive surgical procedures such as urinary derivation and colostomy were necessary in only 0.6 % of the cases.
The urinary incontinence rate reported was insignificant, varying from 0.2 to 2 %; proctitis incidence was 6 %.
Impotence also registered a low prevalence, varying according to age and sexual performance before implantation. In young patients, who previously had a good performance, potency was preserved in 80% of the cases, though these data are hard to evaluate due to their extreme subjectivity.

CONCLUSIONS

The rate of biochemical control for early stages of prostate cancer achieved with isolated brachytherapy is 83% after 7 years, thus comparable to that of radical prostatectomy for carcinomas with a low degree of malignancy. For patients that receive an association of brachytherapy and external radiotherapy, the biochemical control rate after 7 years is 73%, slightly better than if they were treated with isolated external radiotherapy. The higher effectiveness of the combined method can be explained by the larger amount of radiation that may be delivered to the prostate gland, with the implantation of radioactive seeds.
Results of brachytherapy after 10 to 15 years are not yet available, but are anticipated, so that this technique can be recognized as the ideal method for treating early stages of prostate cancer.
Further information can be obtained through direct contact with our medical staff at Radioterapia Botafogo by phone, fax or e-mail.