Brachytherapy is radiation therapy incorporating placement of either temporary or permanent radioactive isotopes into precisely determined parts of the prostate as a combined urological and radiotherapy procedure. Permanent (also known as Low dose rate, LDR) brachytherapy, or temporary ( high dose rate , HDR ) brachytherapy may be advised by your specialist; there are differing indications for their use, and different side effects, results and costs involved. Only a few centres around Australia have very significant and long term experience with these techniques, and Dr Coombes is part of the very active brachytherapy program at the Mater Hospital, together with radiotherapy specialist Dr Colin Chen.
Iodine seed (permanent, low dose rate or LDR ) brachytherapy is of use in the treatment of early, low stage, low grade cancer. To be successful in cancer control (and to be eligible for some rebates) the criteria include a clinical stage of T2c or less ( no palpable cancer extension beyond the prostate) , a PSA value of less than 10, and a Gleason sum less than 7 out of 10 . This may exclude some men with prostate cancer, but in fact those men with that more aggressive disease pattern would be better off with the other treatments, either surgery, or high dose rate (HDR) brachytherapy (see below) . A previous TURP ("rebore") operation may be an exclusion to seed brachytherapy, because of the possibility of seed migration.
Once LDR brachytherapy has been discussed and agreed on by your urologist and radiation oncologist, an outpatient planning transrectal ultrasound probe "volume study" (and transient urinary catheter) is carried out to determine the physical suitability of the gland in comparison to the planned radiation template, and if the prostate is too large, hormonal blockade (depot injections of a testosterone blocker) is given to reduce the prostatic size over 3 - 6 months . When the prostate is small enough, computerised data is measured and the iodine seeds can be ordered from the USA. The treatment session itself takes 1 -2 hours with the placement of 60 - 100 seeds via the perineum into the prostate, ultrasonically guided. It requires an anaesthetic and usually a day stay in hospital with a catheter in place. For some men it provides the quickest recovery from prostate cancer treatment. There is little in the way of erectile dysfunction in the short term.
In the first few months post treatment there may well be urinary frequency and urgency (irritative bladder symptoms). Occasionally there will be swelling of the gland and retention of urine such to require a catheter for several weeks. A post op MRI scan is carried out usually at one month to calculate seed position and to determine the overall dosage. In up to 10 % of patients, there may be one or more "cold spots" which then require some additional seeds placed, or a course of external beam radiotherapy. Follow up PSAs are measured each 3 months post treatment with visits alternating between the urologist and the radiotherapist. After 18 months the measurements are done each 6 months. There may be a PSA 'bounce' at 12 - 18 months, but long term we expect to see PSA readings below 1 ng/mL.
Temporary (high dose rate or HDR) brachytherapy is a treatment option for more locally advanced disease. There must be no evidence of distant or lymph node spread. High grade cancer or even T3 (extracapsular) disease can be treated this way. It involves again an ultrasound volume study to assess gland size for template suitability. The pulses of radiation are given after the placement of 17 - 20 hollow plastic needles via the perineum under an epidural anaesthetic and sedation . You are in hospital for 36 hours with bed rest, a urinary catheter and an epidural, during which time a progress CT scan is performed and the dose calculated to conform with the shape of your prostate. 2 pulses of high dose rate radiation are given over 24 hours while in hospital, then the needles and catheter removed. After a 1 - 2 week break, you then have 6½ - 7 weeks of external beam radiation to bring the full dose up. 3 monthly PSA testing is again monitored, with visits alternating between the radiation oncologist and the urologist. Side effects may be encountered such as blood or clots in the urine , bladder irritability, rectal discomfort and loose bowel motions, and a gradual development of erectile dysfunction. Urinary incontinence is uncommon following brachytherapy, but in the long term there can be 5 - 10 % risk of a scar or urethral stricture which can be significant. Your radiotherapist will fully outline the potential benefits and risks inherent with each form of treatment.
3D Conformal external beam radiotherapy and IMRT, without a brachytherapy boost, is also used as a curative treatment for early prostate cancer. It is used in men with significant medical co-morbidities, or where the possible side effects of brachytherapy may be excessive. It involves CT or MRI planning of the radiation fields, and treatment at an RT facility daily Monday to Friday for 6 - 7 weeks. It is commonly combined with a 1 to 2 year course of androgen deprivation therapy (male hormone blockade). It is also used in the palliative treatment of bony cancer deposits, or as a post operative treatment for pelvic cancer recurrence.