A low dose rate prostatic brachytherapy implant involves the insertion of radioactive pellets (seeds) directly into the prostate via a transperineal approach (the needles are inserted through the muscle between the scrotum and rectum). These radioactive seeds slowly emit their radiation over a long period of time with a half life of approximately two month. In other words the total radiation dose is usually delivered over a 10 month period (5 half lives).
It is possible that the constant delivery of low dose radiation over this period of time may improve outcome, as the constant radiation dose does not allow for repair of prostate cancer cells between each usual fraction of external beam radiation.
Why would I choose low dose rate brachytherapy over external beam radiotherapy?
There are many reasons why patients choose a low dose rate prostatic brachytherapy implant above external beam radiation to the prostate. Firstly the brachytherapy procedure is performed as either a day case or as a single overnight hospital stay procedure. This compares with radiotherapy delivered daily for a 7 – 8 week period with external beam radiotherapy. Therefore brachytherapy is of a major advantage to patients with respect to early return to work and less disruption to patients lifestyle and working environments This is particularly so for patients who live in the country, that would need to be in major metropolitan centres for up to 2 months whilst receiving external beam radiation treatment.
There is also increasing amount of evidence that suggests that the long term outcome of brachytherapy is superior to external beam radiotherapy, with respect to late biochemical failure (cancer failure). This is because with brachytherapy the radiation is inserted directly into prostate, which increases the amount of radiation delivered to the prostate cancer based on a complex mathematical formula, based on alpha / beta radios. The more radiation delivered to the prostate cancer; the better the chance of curing your prostate cancer.
Is there any difference in side effects between brachytherapy and external beam radiotherapy?
Because the brachytherapy treatment insert radiation directly into the prostate, there is less “collateral damage” to structures around the prostate, particularly the rectum and bowel. Most of the scientific data would suggest less damage to your bowel / rectum with brachytherapy, which results in less risk of long term bleeding, rectal urgency, rectal mucous production and frequency of bowel motion compared to external beam radiotherapy.
There is a large amount of radiation delivered to the prostate urethra, which is the tube that drains urine through the prostate gland from the bladder through to the penis. This is associated with a higher risk of stinging and burning in your urine (dysuria) and a higher risk of urinary frequency and urgency than external beam radiation treatment.
Is there any difference in recovery of erections between external beam radiotherapy and brachytherapy?
Many centre that deliver external beam radiotherapy use hormone therapy prior to the radiation treatment. This has been shown to improve the long term control of cancer from external beam radiotherapy treatment. During the period of hormone treatment patients will lose their erections. Hormone therapy is rarely used with low dose rate brachytherapy treatment in Australia, unless to shrink a large prostate (cytoreduction) prior to a brachytherapy implant, to allow for a technically successful brachytherapy procedure. Therefore there are less patients who will lose erections with brachytherapy during the initial part of treatment if we take into consideration patients that require androgen deprivation therapy with there external beam radiotherapy treatment.
Approximately 25% of patients will become impotent within 2 years of a brachytherapy implant, slightly higher if men have pre-existing erectile dysfunction prior to brachytherapy. Approximately 30% of men will have lost erections 5 years after brachytherapy, with a higher rate of erectile loss in men over the age of 65 years at the time of their brachytherapy implant. These long term figures are similar to external beam radiation therapy outcome.
Is there any advantage between brachytherapy and surgery with respect to long term cure?
There are no randomised clinical studies with a large number of patient and long term follow up which can answer this question. There is some nomogram data available on web sites which would suggest a slightly superior long term “biochemical cure” with radical prostatectomy in similarly matched patient groups. However the clinical publications on outcome between surgery and brachytherapy show similar 15 year survival rates in each treatment group.
Therefore for men with a life expectancy of approximately 15 years (median age 68 years in Australia) there is unlikely to be a significant difference in long term death from prostate cancer whether a patient chooses a brachytherapy implant or a radical prostatectomy. For men younger then the age of 60 years it usually recommended that a patient proceed with a radical prostatectomy until long term 20 – 25 year data on low dose rate brachytherapy is unknown.
Is there any difference in outcome between brachytherapy and surgery with respect to loss of erections and continence of urine?
With modern surgical techniques, including robotic assisted laparoscopic surgery, the quality of life following a radical prostatectomy has been significantly improving over the last 20 years. Despite this, even in high volume urology units, 5% of patients will develop ongoing continence of urine following a radical prostatectomy procedure requiring pad usage. This compares with approximately 1% of patients who undergo a brachytherapy implant.
With modern nerve sparing techniques there has also been improvement in the long term recovery of erectile function after a radical prostatectomy.
While some patients who are treated with low dose rate brachytherapy can lose erections, the chance of losing erections with low dose rate brachytherapy does appear to be less than with a radical prostatectomy procedure, particularly with patients over the age of 65 years at the time of treatment.
There is less risk of bothersome long term bladder symptoms, stinging and burning of urine, and rectal complications with a radical prostatectomy compared to a low dose rate brachytherapy implant.