This is a form of radiation therapy used for prostate cancer. The term brachytherapy refers specifically to the implantation of radioactive pellets or seeds into the substance of the prostate. Brachytherapy is thus to be contrasted with the more commonly performed external beam radiation treatments for prostate cancer, which can be referred to as prostatic "teletherapy", the latter term rarely used in everyday practice. Prostatic brachytherapy--implanting radioactive seeds into the prostate to treat localized prostate cancers--is not a new concept, but one which has been available in some form for decades. Its theoretical advantages are the ability to target high energy radiation directly inside the prostate where the cancer is while minimizing radiation to normal tissues and organs which surround the prostate.
In theory, this allows more radiation energy to be applied to prostate cancer without causing much harm to the rectum, bladder and other typical structures. One might think of prostatic BRACHYTHERAPY as radiating the prostate from the inside out rather than directing radiation from the outside in (and necessarily passing through all surrounding organs), as is done during external beam radiation of the prostate. This brings up a theoretical disadvantage of brachytherapy compared with external beam radiation" that is brachytherapy's relative inability to treat tissues outside of the prostate, including the seminal vesicles and local lymph nodes which might represent sites of the early spread of prostate cancer. The actual radioactive pellets or seeds currently used for prostatic brachytherapy are small, metallic, cylindrical objects about the size of the tip of a leaf pencil. Radioactive isotopes of the chemical elements iodine or palladium are typically used to make these seeds. After years of relative disuse, prostatic brachytherapy is currently enjoying a resurgence of clinical application and availability.
The reasons for this resurgence in interest in this form of radiation treatment for prostate cancer are primarily related to much improved technological approaches to implanting radioactive seeds in the prostate. In older techniques, radiation seeds were implanted during an open surgical procedure that was not dissimilar to the pelvic dissection required for radical prostatectomy or surgical prostate removal. Thus, patients were exposed to all of the problems and morbidity associated with a major operation. In older techniques, the guidance for placing seeds in the prostate was primarily the "feel" of the surgeon's fingers and was relatively crude.
It was quite difficult to achieve an even distribution of seeds and this of radiation energy throughout the prostate. Using such older techniques, it was difficult to demonstrate that prostatic brachytherapy was as good as standard external beam radiotherapy--and certainly it was no better-- even though it was much more difficult for the patient. These reasons explain why it fell into disuse by most urologists and radiation therapists.
The latest technological advances in prostatic brachytherapy revolve around the use of transrectal ultrasound imaging of the prostate. Before treatment with modern prostatic brachytherapy, the surgeon will perform a careful transrectal ultrasound exam of the patient's prostate, in essence creating a detailed anatomic map of the prostate to guide later implantation of radioactive seeds. This map of the prostate is then fed into one of several available computer programs, which plot the exact placement of radioactive seed throughout the prostate to achieve optimal radiation implantation.
When it comes time for the actual implantation of radioactive seeds, transrectal ultrasound guidance is used again by the surgeon and the radiotherapist, together with the previously made prostate map and computer plotting of seed distribution, to carefully place each radioactive seed in the prostate in the exact location computed for optimal radiation treatment.This ultrasound-guided approach is now combined with the use of relatively small bore needles placed directly through the patient's skin ("percutaneously") behind his scrotum and in front of the rectum (anatomically, this small area is called the "perineum"). The surgeon can see each needle entering the prostate with the transrectal ultrasound and can guide its exact placement. Through these needles, the small radioactive seeds are literally pushed into the substance of the prostate.
In a typical prostatic brachytherapy treatment for prostate cancer performed today, a few such needles may be placed into the prostate, and over a hundred radioactive seeds may be positioned throughout the prostate gland.
With this "percutaneous" approach to the prostate(puncturing the skin only with a needle), there is no incision and thus minimal postoperative discomfort or prolonged time required for healing. Compared to the older techniques for prostatic brachytherapy, which required an incision and then allowed only crude control placement of radioactive seeds, the newer technology offers obvious advantages.Modern prostatic brachytherapy is performed in an operating room with the patient under some form of anesthesia. In order to achieve the high-tech accuracy of seed placement in the prostate desired using this technology, the patient must remain perfectly still for the duration of the implantation procedure, which typically takes about an hour. After the operation, the patient may go home the same day or be discharged the next day after overnight hospitalization.
This depends, at least in part, on the patient's other medical problems and overall physical condition. The patient may or may not be required to go home with a small urinary catheter or tube to drain the urine for a few days after the operation.In addition to theoretically improving prostate cancer treatment because of more accurately controlling radiation doses throughout the prostate, the more accurate placement of radiation energy afforded by these new brachytherapy techniques using transrectal ultrasound guidance also theoretically should produce fewer complications related to radiation injury to normal tissues and organs around the prostate.As currently practised, the major short-term problems experienced by patients treated with prostatic brachytherapy are difficulty with urination immediately after the operation. Many patients will require a urinary catheter or drainage tube for a few days or sometimes a few weeks after undergoing prostatic brachytherapy. Bleeding and infection are uncommon complications.
Patients with very large prostates and patients who have received prostate surgery (such as transurethral resection of the prostate, or "TURP") are usually excluded from treatment with prostatic brachytherapy and should consider other forms of therapy. In some cases, hormonal treatments can shrink an enlarged prostate before proceeding with brachytherapy. Preliminary data indicate that the latest forms of prostatic brachytherapy may be superior to standard external beam radiation therapy to control prostate cancer. The very best results reported for any radiation treatment seem to be achieved by combining a limited course of external beam radiation therapy with the modern technological approach to transrectal ultrasound-guided prostatic brachytherapy.
However, because this technology is relatively new, all of these results must be interpreted cautiously since the long-term results of this therapy are necessarily limited at this point.It must also be remembered that the "gold standard" for the cure of prostate cancer is and remains the successful surgical removal of the prostate and cancer at radical prostatectomy. No form of radiation therapy, including modern prostatic brachytherapy techniques, is equal or superior to radical prostatectomy in this regard.