Brachytherapy (also known as interstitial radiotherapy) involves the placing of radioactive implants into the prostate gland. The implants are placed under general anaesthetic using radiological guidance. The implants can be either permanent or removable. Isotopes currently used include: Iodine-125, Palladium-103 and Iridium-192.
Permanent implants are the commonest form of prostate brachytherapy. The implants are left within the prostate and deliver radiation over several months. The main advantage of permanent implants is that the treatment is completed in a single application, which can often be done as an out-patient procedure, or with a single overnight stay in hospital.
Removable implants use needles or tubes, which are placed in the prostate and can be after-loaded with the radioactive source. These are then removed on completion of the treatment.
Brachytherapy may sometimes be used in conjunction with hormonal therapy.
Brachytherapy is not suitable for all men with early prostate cancer. Current selection criteria are (22):
- no previous TURP
- histologically confirmed adenocarcinoma of the prostate
- disease confined within the prostate capsule (stage T1–T2) as confirmed by transrectal ultrasound and/or MRI scanning
- no evidence of metastatic disease
- prostate volume less than 60 cc - may be possible to shrink the prostate with 3–6 months of hormonal therapy before brachytherapy
- PSA < 20
- Gleason < 7.
The most common unwanted side effect of prostate brachytherapy is urethritis. Other side effects include varying degrees of urinary frequency, impotence, acute retention, incontinence and dysuria. A disadvantage for medical staff is the need to handle radioactive sources (23).
There have been no randomised controlled trials comparing brachytherapy with any other treatments used for early prostate cancer.