For GPs

Brachytherapy for Prostate Cancer

Brachytherapy is a form of radiation therapy, where a source or multiple ‘seeds’ of radiation are placed into the prostate. This allows very high and localised doses of radiation to be delivered to the prostate. The radiation from these sources usually only penetrates a few mm of tissue, reducing the exposure to the surrounding tissues. This allows for an increased dose to the prostate and at the same time reduces the toxicity to the normal healthy tissues. There are 2 types of Brachytherapy used or prostate  cancer:

Low dose rate (LDR) or seed brachytherapy

How it works

In this type of brachytherapy, small seeds of radioactive Iodine ( Iodine- 125) are placed into the prostate. Each seed is 5mm long and 1mm wide and 80 to 120 seeds would typically be used. These seeds deliver a high dose of radiation but do so over a long time (a low dose rate).  As they are placed within the prostate, this allows a high dose to be delivered directly to the tumour with minimal dose to the surrounding healthy organs, such as the rectum and bladder.  Using this technique provides a very high chance of cure for suitable patients with reduced side effects.

Who is suitable?

This treatment is suitable for lower risk, localised prostate cancers. There are some requirements that the radiation oncologist will discuss.

What are the benefits and side effects?

The main advantage of brachytherapy is the reduced long-term toxicities. However, there is still a small risk of urethral scarring and long-term change in bladder habit. Like all other prostate cancer treatments, there is a chance that men can develop erectile dysfunction. However, it seems that this risk is lowest with seed brachytherapy. Approximately 30-40% of men will have some erectile problems after LDR brachytherapy.

One of the other big advantages of this treatment is convenience. It typically requires 2 – 3 visits to the hospital with up to 1 night in hospital.

What is the procedure for treatment?

The first visit is for a volume study needed to plan where the seeds will go. A general anaesthetic is often given for this and it involves obtaining a rectal ultrasound. Following this the plan is generated by medical physicists and radiation therapists. The safety and effectiveness of the plan is checked by the radiation oncologist. The plan is a 3D model of where the seeds need to be placed, in order to deliver the appropriate dose and coverage of the cancer. Once this has been completed, the seeds are ordered and preloaded into needles, ready for the seed insertion procedure a few weeks later.

The implant procedure involves an anaesthetic and takes about 1 ½ hours. The radioactive seeds are methodically placed into the prostate through the perineum (skin between the scrotum and anus) using 20-30 thin needles.  Once completed men usually go home that afternoon or the next day.  A check CT scan or MRI is performed a few weeks later to ensure that the seeds are in the correct position to allow the radiation to cover the prostate gland adequately.

Results of LDR brachytherapy

The seed brachytherapy technique is now well established and large studies suggest the outcomes are at least as effective as external beam radiotherapy and surgery.

For more information about this technique  watch the video.

In March 2016, Donald Patterson was the 400th man to be treated with LDR brachytherapy in Australia. View his experience.

High dose rate (HDR) brachytherapy

How it works

This is a form of brachytherapy using a single high energy radioactive source to deliver a high dose to the prostate over a short time. It is nearly always used in addition to external beam radiotherapy as a “boost”, enabling a higher dose to be delivered to the prostate cancer.

Who is suitable?

This treatment may be used for men with higher risk (more locally advanced) prostate cancers.

What are the benefits and side effects?

The main advantage of HDR brachytherapy is that it delivers a higher dose directly inside the prostate than can typically be delivered with external beam radiation therapy alone. It is usually part of a package of treatment that includes external beam radiation therapy.

The side effects include temporary bladder irritation and bruising from the needles. In the long term the treatment risks are similar to external beam radiotherapy. There is a slightly higher risk of urethral scarring (strictures) and bladder irritation in the long term.

What is the procedure for treatment?

HDR brachytherapy is delivered using a machine called a remote after loader which contains a small, highly radioactive source (e.g. Iridium-192). Thin blind-end hollow needles are inserted into the prostate and only remain in for the time needed to deliver the treatment. The radioactive source is then driven through each needle, pausing along the way to deliver a pre-planned and accurately shaped radiation dose. This takes only a few minutes and may be repeated for a number of treatment ( usually 1-4). Once the HDR treatments are finished the needles are removed.

This procedure requires patients to have either a spinal or general anaesthetic and spend up to 24 hours in hospital without getting out of bed.

Results of  HDR brachytherapy

Results of HDR brachytherapy in terms of long-term cure/control of prostate cancer are at least as favourable as external beam radiation therapy or surgery (radical prostatectomy).

Useful Resources

What is brachytherapy and how effective is it for prostate cancer? Interview with A/Prof Jeremy Millar, Director, Radiation Oncology, Alfred Health.