Radiotherapy

taken from Small Gland, Big Problem 4th Edition
by Professor Roger Kirby, Health Press 2011

Radiotherapy is most appropriate for the older man whose cancer is confined to the prostate or surrounding area. But it is also suitable for the younger man whose general health precludes major surgery or in men who are worried about the side effects of surgery. With this type of treatment, radiation is applied to the affected area – the prostate and surrounding tissues – to destroy the cancer cells, leaving normal cells relatively unaffected. You may be offered one of two types of radiotherapy: external-beam radiotherapy is the most commonly used, but another method, called brachytherapy (see page 41), is also becoming more widely available.

External-beam radiotherapy

As the name suggests, a beam of radiation generated by an external source is directed at your lower abdomen. This is normally an outpatient procedure, and the most usual pattern is 20–30 minutes of treatment, 5 days a week for 6–7 weeks.

radiotherapy
With external-beam radiotherapy, X-rays are produced by an external radiation source and focused on the prostate from three directions

About 3 months before the radiotherapy, you will usually be given hormone therapy (see pages 58–60). This shrinks the prostate tumour so that the radiation is more likely to destroy the cancer cells, which are now concentrated in a smaller area. Be aware that these hormones may affect your sex life.

A newer form of radiotherapy – conformal radiotherapy (CFRT) – has now been introduced. The use of a so-called ‘multi-leaf collimator’ allows more accurate targeting of the cancer and so carries a lower risk of side effects – ask your radiotherapist whether it is available in your area. The very latest form of radiation treatment is intensity-modulated radiotherapy (IMRT), which allows high doses of radiation to be precisely shaped to the individual patient’s prostate. This very expensive high-technology equipment is likely to become increasingly available over the next few years.

CyberKnife uses image guidance of the body and computer-controlled robotics to deliver with great accuracy around 1200 beams of high-energy radiation to the tumour. The aim is to target the tumour with radiation strong enough to kill the cancer cells while leaving the healthy surrounding tissue intact.

The treatment duration is short, perhaps only a week, but long-term follow-up data are required before it becomes an established treatment.

Possible side effects and risks. The main side effects of radiotherapy are bladder irritation and a need to urinate more often. Usually these effects are mild, though a very small proportion of men will be severely affected. You may also feel irritation or discomfort in and around the rectum, and notice some diarrhoea and bleeding; these effects are usually temporary, lasting only for a few weeks, but may persist for a longer time in some men. Recently, it has been reported that men who have undergone pelvic irradiation for prostate cancer have a slightly higher risk of developing rectal cancer, so you should see your doctor if you have any bleeding from the back passage some time after treatment.

A proportion of men who have undergone radiotherapy will develop problems with erections as a result. This problem tends to develop gradually over 6–12 months, but can usually be overcome with the use of treatments such as Viagra (sildenafil), Cialis (tadalafil) or Levitra (vardenafil) or prostaglandin injections.

Brachytherapy

Brachytherapy has become popular in the USA and is becoming available at an increasing number of centres in the UK. It involves the implantation of radioactive pellets into the prostate, so the radiation is emitted from inside rather than from an external source (as is the case with external-beam radiotherapy). The pellets are left inside the patient where they gradually lose their radioactivity over the following 12 months.

brachytherapy
In brachytherapy, radioactive pellets are implanted directly into the prostate

Before the pellets are implanted, the radiotherapist will need to assess your prostate exactly. In order to do so, an ultrasound probe will be inserted into your rectum so that an ultrasound scan can be seen on a computer screen. The pellets – usually between 60 and 100 – are then put into your prostate using needles inserted under general anaesthetic through the skin between your scrotum and rectum. You will usually be fitted with a catheter to help you pass urine after the operation, which will have to stay in place for 12 hours or so, but you can normally go home within 24 hours. After brachytherapy the PSA levels gradually decline, but not usually to as low a value as after surgery.

x-ray
An X-ray showing the radioactive pellets in place in the prostate. The larger dots in the shape of a cross are used to help target the prostate

Brachytherapy is most suitable for patients with smaller lower-risk cancers and for men who have small or medium-sized prostates. If a TURP (transurethral resection of the prostate; see page 82) has been performed previously to treat BPH, the radioactive seeds cannot be sited correctly in the gland. Pre-treatment with prostate-shrinking drugs, such as LHRH (luteinizing hormone releasing hormone) analogues, can sometimes make brachytherapy suitable for men with especially large glands. Brachytherapy is not appropriate for men whose cancer has spread beyond the prostate.

Possible side effects and risks. Up to 10 years after treatment, the results appear to be good in terms of keeping the PSA level down and local cancer control. As the radiation is being targeted at the prostate so accurately, urinary problems and rectal damage are probably less common after brachytherapy than after external-beam radiotherapy. Problems with potency, though, are still common. One problem with brachytherapy is that it is difficult to treat a cancer that recurs following this treatment, as surgery in this situation is risky.