Brachytherapy is the treatment of prostate cancer by the implantation of radioactive isotope (sealed or encapsulated into 'seeds') into the prostate.
This method has reached a very advanced level of sophistication in the last ten years due to improvements in ultrasound imaging of the prostate during the procedure (allowing direct visualisation of the deposition of the seeds) and better computer assisted planning and seed delivery mehtods.
The great attraction of brachytherapy is that it is a single procedure, that amounts to a small operation, with the patients almost always leaving hospital next day.
Brachytherapy depends on the "inverse square law" of physics; this states that around a source of radiation, the dose 'falls off' at the square of the distance. Thus, the tissues around the prostate receive a much lower dose than anticipated by other radiation methods and, because of this, the doctor is able to safely deliver a very high dose to the prostate cancer with low risks to adjacent structures
The inclusion of patients for brachytherapy is defined by relatively strict criteria. You can
view a decision algorithm for brachytherapy. This explains how a doctor makes the decision as to whether brachytherapy is the appropriate treatment. Usually, we accept those biopsy proven patients with a Gleason score less than 8, a gland of less than 50cc, good urinary flow rates and a PSA of less than 15.
Patients are excluded from brachytherapy as monotherapy if their Gleason grade is > 7, their PSA levels are > than 18 ng/ml or if their clinical stage > T2
These early stage patients are likely to have a very good prospect for cure by any of the three standard curative therapies viz. external beam (conformal/IMRT) radiotherapy, brachytherapy or surgery, and it is for this group of patients that there is a real choice of therapies - for the ten year disease-free survival figures are equivalent after any one.
For some patients (e.g. the patient with a single focus of Gleason grade 3 tumour) there is a low chance of early progression of the cancer without any active treatment, and particularly where there are other potentially serious medical conditions e.g. heart disease, there may be no indication for specific therapy for the prostate cancer at the time of diagnosis.
For patients with a slightly higher risk profile e.g. a multifocal Gleason 7 cancer, a serum PSA of e.g. 18 and the suggestion of capsular breach on the MRI, then a mixed external beam radiotherapy followed by brachytherapy approach yields excellent cure results.
The Procedure
The delivery of interstitial brachytherapy is nowadays carried out with great precision, utilising trans-rectal ultrasound to visualise the prostate and allow the radioactive seeds to be placed under direct supervision.
After initial assessment and fulfilling the entry criteria for inclusion in brachytherapy treatment, the patient is usually admitted to hospital for forty eighthours. On the first day, a bowel 'clear out' is performed via enemas, in order that the transrectal probe has a clear view of the prostate at the operation.
On the next morning, patient is anaesthetised, an ultrasound probe is inserted into the rectum and multiple measurements taken to assess the dimensions and configuration of the prostate and its relationship to other structures, such as the urethra.
