Radiation Therapy

Radiation Therapy (RT) is either given as a radioactive seed implant within the prostate ( Low Dose Rate Brachytherapy) or as external beam therapy known as IMRT (Intensity Modulated Radiation Therapy).

RT uses high energy x-ray beams to kill cancer cells. The x-ray energy hits cells in their path causing damage to the DNA of the cells. The damaged cells try to repair their DNA, however the cancer cells are more susceptible to radiation as they tend to divide and multiply at a much faster rate than normal cells.

External Beam Radiotherapy / IMRT

Up until the 1990's radiotherapy for prostate cancer was relatively ineffective. To begin with it was mainly used in cases where the cancer was too advanced to cure. Also the dose of radiation used was too low to control the majority of cancers. All this changed when CT scan was introduced. This enabled the prostate cancer to be accurately targeted, and the rectum and bladder to be excluded from the radiation field. As a result radiation doses were dramatically increased along with cure rates.

IMRT intensity modulated radiotherapy is a way of delivering radiotherapy so that the radiation dose is curved around normal tissues allowing higher doses to be given safely. This enables the treatment days to be increased without excessive injury to the rectum.

The treatment is given Monday to Friday for seven to eight weeks. Each treatment takes about 15 minutes a day. It is completely painless. The frequency of bowel movements and passing urine can increase during the treatment and some tiredness develops about halfway through the course, these short-term side effects usually settle down within 3-6 months.

IMRT is usually combined with Hormonal Therapy for 6-24 months, also known as ADT (Androgen Deprivation Therapy). This means regular injections of drugs to cause a chemical castration while you receive IMRT, and in some cases for up to 2 years. ADT has its own set of side effects, which tend to linger even after the injections have ceased.

LDR Brachytherapy

Brachytherapy seed implantation is a radiation treatment for early localized prostate cancer. At present it is recommended for cancers of Gleason score 6 and 7 cancers, PSA <10, in men with relatively small prostates, minimal urinary symptoms and a normal urine flow as measured by Uroflometry.

The main advantage of brachytherapy is that it can deliver higher and more precise doses of radiation to the prostate gland in excess of what can be achieved with external beam radiation treatment.

There are two major forms of prostate brachytherapy.

1. Permanent Low Dose Rate seed prostate brachytherapy.
2. Temporary High Dose Rate prostate brachytherapy.

Permanent LDR Seed Prostate Brachytherapy

This Involves the permanent implantation of tiny seeds containing radioactive iodine 125 into the prostate where they give off low dose rate radiation for approximately 6 months.

This is a multi step process involving a planning and a treatment phase.

In the planning phase a volume study is performed. This is an examination to determine the size and shape of the prostate. Ultrasound images of the prostate are then used to determine the number and precise location of the radioactive seeds to be positioned within the prostate to treat the prostate cancer.

The implant procedure is performed under a general anaesthetic, the I -125 seeds are preloaded into thin needles which are passed onto the prostate gland through the skin between the scrotum and anus. As the needles are passed into the prostate their progress is visualized on an ultrasound machine to ensure accurate placement of the seeds. Their position has been predetermined by the planning phase. Usually 90-120 seeds are required.

Following the seed implantation a cystoscopy (examination of the bladder) is performed and a catheter may be inserted into the bladder overnight, after which it is removed the next day.

Many patients then resume normal activities within a few days to weeks.

Post LDR Brachytherapy

• Urinary Symptoms

  Following the procedure urinary frequency, burning and dribbling commonly occur after the implantation. Tamsulosin is prescribed for a 3 month period to reduce these symptoms. In about 5% of men these symptoms are troublesome enough to require the temporary insertion of a catheter. Rarely a patient will still be unable to urinate due to swelling of the prostate following the seed implantation and these patients may need placement of a longer term catheter or to learn self catheterisation.

  If operative treatment for an obstructed prostate is required following seed implantation (ie TURP or transurethral resection of the prostate) the risk of urinary incontinence is much higher than normal (approximately 20-30% compared 1%). Therefore TURP is not recommended following LDR Brachytherapy.

  It is far better to sort out this potential problem before having LDR Brachytherapy, or avoid it completely.

• Sexual Function

  Impotence or loss of erectile function resulting from LDR Brachytherapy is approx 30-50% after 3 years. Most men will respond to Viagra or similar medication during the initial few years.

  Following the implant men can develop a dry ejaculate. Reduced ejaculation of seminal fluid is due to fibrosis of the prostate tissue in response to radiation injury.

  Penile numbness occurs occasionally and can last 1-2 months. The numbness will resolve on its own and requires no specific treatment.

  There will be some dark blood in your ejaculate or some pain at orgasm with your first few ejaculates.

• Diarrhoea

  Loose bowel motions and faecal frequency is common following brachytherapy. It may be treated with medication and usually settles within 3 months.

• Scrotal Swelling and Bruising

  There may be some bruising and swelling of the scrotum. This lasts 3-4 weeks and resolves by itself.

• Pain

  Some men have mild to moderate pain at the implant site. This is usually relieved with over the counter pain killers.

Follow Up Schedule

A month following the seed implant a CT scan is performed which reviews the exact position of each seed in the prostate. This is necessary to determine that your prostate is receiving the proper amount of radiation throughout the entire gland.

You will see your Urologist and Radiation Oncologist on a regular basis with PSA testing. The PSA reaches it's lowest level at 3-4 years (PSA nadir) and a reading <0.5 indicates the highest chance of a cure. There is a ‘PSA bounce’ in 50% of men in the first 1-2 years after brachytherapy. This indicates a good response to treatment, but can be disconcerting if you are not aware of the PSA bounce.

PSA Relapse occurs in men if the prostate cancer has recurred. The definition of PSA relapse is known as the Phoenix Criteria, not because the cancer has arisen from the dead according to Greek mythology, but because a consensus statement was derived in Phoenix Arizona.

The Phoenix Criteria states that PSA nadir + 2.0 = PSA Relapse after RT.

For example your PSA nadir is 0.5 after 3 years, but hits 2.5 after 5 years, this means the treatment has failed to cure the prostate cancer.

In practical terms, this usually means reverting to a Watchful Waiting program, since salvage surgery is not regarded as safe or very effective after failed LDR Brachy.

You should bear this in mind when deciding on the best treatment option.

Temporary High Dose Rate (HDR) Prostate Brachytherapy

In this procedure temporary needles are placed inside the prostate and the needles are left in place for approximately 36 hours while the patient remains in hospital. These hollow needles allow a radioactive source to be placed in several different positions within the prostate, and this process is repeated 2-3 times with a 6-8 hour gap between each treatment.

The potential side effects are similar between high dose rate brachytherapy and permanent seed brachytherapy except that blood in the urine, erectile dysfunction and scarring in the urethra is more common after high-dose brachytherapy.

HDR brahytherapy is indicated for locally advanced and higher risk prostate cancer as an alternative to radical prostatectomy and external beam radiation.

Late Onset Complications of Radiation Therapy

The late onset complications of RT occur after more than 5 years and as long as 20 years following RT for prostate cancer. These complications can be devastating and life threatening problems, which fall into the lap of Urologists to manage, long after the Radiation Oncologist has treated the patient.

Urologists are therefore very aware of these problems, and the difficulty of managing late onset complications.

• Haemorrhagic Radiation Cystitis presents as blood in the urine or haematuria, and is diagnosed with Cystoscopy examination of the bladder.

  In mild cases treatment with Hyperbaric Oxygen Treatment (HBOT) requiring 40 sessions in a hyperbaric chamber, can be beneficial.

  In moderate cases a bladder irrigation with chemicals such as Aluminium Hydroxide (Alum) or Prostaglandin, can help to stop the bleeding.

  In more severe cases admission to hospital for Cystoscopy and Laser Ablation of bleeding from the bladder, blood transfusion, temporary percutaneous urinary diversion or ultimately total cystectomy and ileal conduit diversion.

• Urethral Stricture presents as reduced uroflow and symptoms of obstructed voiding. Cystoscopy examination shows a scarred urethra usually very close to the urinary sphincter, which means surgical treatment is very likely to cause urinary incontinence.
  The urethral stricture is therefore treated with self dilatation using a stiff plastic catheter passed along the urethra, to maintain a patent urethral channel.

• Rectal Fistula presents as urinary tract infection, passing urine from the rectum and passing faeces material in the urine. This is very rare late onset complication, but requires a permanent colostomy and suprapubic urinary catheter.

• Bladder Cancer presents as blood in the urine and needs to be differentiated from Haemorrhagic Cystitis with a CT scan and Cystoscopy examination.
  SEER data from a USA database of 340,00 men over 35 years, reported a 14 to 21 fold greater risk of bladder cancer compared to the general population, after 10+ years since prostate RT. The bladder cancers were noted to be higher grade and most common after Brachytherapy compared to EBRT.
  We have performed Salvage Radical Cystectomy & Prostatectomy for bladder cancer after prostate Brachy or EBRT, and this is a high risk surgery for bleeding and rectal perforation. These men have required permanent urinary conduit diversion to a urostomy, and in some cases a permanent colostomy.
  There is a place for screening men for bladder cancer after 10 years since prostate RT with Urine Cytology and Cystoscopy.

These late onset complications from prostate RT are not common, but can be devastating if it affects you.

For these reasons, we believe that RT for prostate cancer is most appropriate for men who;

1. Are not able to have surgery due to other medical issues.
2. Need adjuvant RT after surgery.
3. Older than 70 with a life expectancy of less than 15 years.