External Beam Radiotherapy

This is radiotherapy given by using ionising radiation (for example, high energy X-rays) produced in a machine and directed at the tumour from outside the patient. It is used:

  • with the aim of getting rid of the cancer (curative radiotherapy)
  • after or in conjunction with another treatment
  • to reduce pain and other symptoms in advanced cancers (called ‘palliative radiotherapy’).

Cancer cells differ from normal body cells in that they reproduce faster and are thereby more susceptible to high-energy rays. So repeated exposure to high-energy rays will kill off cancer cells but allow normal cells to recover. Not all cancer cells act in the same way, so it is necessary to adjust the exposure and duration to achieve optimum effect. The treatment itself is painless. It normally involves daily attendance, 5 days a week, at a radiotherapy centre for short sessions for 4 weeks and in some cases up to 7 weeks.

Radiotherapy has been proven to improve overall survival in treating locally advanced disease. Compared with Hormone treatment alone, radiotherapy halves the risk of dying from prostate cancer. The ProtecT trial has shown that radiotherapy is as effective as surgery for men with localised prostate cancer. It can be used in combination with Brachytherapy and Hormone treatment for men with intermediate- or high-risk localised prostate cancer.

Conformal radiotherapy

This has been in common use for many years and, until recently, was the standard method of delivery for prostate cancer patients. The radiation beam is shaped to reduce the radiation to the surrounding areas, but it is unable to provide the detailed targeted coverage that newer technologies can offer. Recent developments in the field of radiotherapy include: Intensity Modulated Radiation Therapy (IMRT) and Image Guided Radiation Therapy (IGRT). These are described in detail below.

IMRT

IMRT takes conformal radiotherapy a step further in the precision by which the beam is shaped and directed at the body, typically from five different angles. A high degree of planning and computer control is involved in these processes, requiring more time in the treatment sessions. This technique uses multiple beams of varying intensity to achieve complex shaping of the radiation dose around the prostate. Many small ‘beamlets’ from various angles contribute to the total dose administered. These methods help to reduce some of the possible side effects. Now widely available in the UK, this equipment is impressive, with good short-term results.

The latest data from the National Prostate Cancer Audit shows 90% of patients in England and 100% in Wales are treated with IMRT. Tomography is also a form of intensity modulated radiation therapy (IMRT).

  IMRT IMRT Linear accelerator

IGRT

This is a form of IMRT but even more accurate. The technique uses regular imaging of the tumour or a marker inserted into the prostate before treatment. It is used to confirm that the target and surrounding organs are truly in a position appropriate for the therapy. In prostate cancer, IGRT can be achieved by implanting small inert seeds (fiducial markers), or a cone beam CT scan can be taken once the patient is in the treatment position.

Fractionation or Radiation Dosage

The dose of radioation is measured in Grays (Gy). Recently announced outcomes from the CHiPP clinical trial, NICE Prostate Cancer guidelines (2019) confirm that for low- and intermediate-risk localised prostate cancer patients, hypofractionated radiotherapy (60 Gy delivered in 3 Gy fractions), requiring 20 treatment sessions, should be offered.The previous standard of 74 Gy delivered in 37 sessions of 2 Gyfractions may be used in certain cases.

For cancer recurrence after radical prostatectomy, a total of 66 Gy in 2 Gy fractions is normally used, requiring 33 treatment sessions.

Radiation with Hormone treatment

Clinical trials have shown a benefit in patients who receive Hormone treatment with radiation treatment; studies have shown that this combination increases long-term survival. It is now becoming the standard treatment for men with certain types of intermediate-risk prostate cancer and nearly all high-risk.

Side effects of radiotherapy

For prostate radiotherapy, the short-term side effects can be bladder and/or rectal irritation, including blood in the urine or rectum. Long-term side effects can include alteration of bowel habit and impotence problems. As with other treatments, ejaculatory function may be either lost or degraded. Because of damage to adjacent tissues, there is some evidence of a small risk of developing bladder or rectal cancer 10 or more years after treatment. These side effects should be discussed in detail with your consultant oncologist prior to your agreement that the treatment should proceed.

Note: When receiving radiotherapy, it is important to follow the dietary advice given by your doctor and radiographers who are treating you daily.

SpaceOAR Hydrogel©

This procedure can benefit prostate cancer patients receiving radiotherapy and has been designed to reduce radiation exposure to organs surrounding the prostate. This therefore might reduce the potential of long-term side effects and damage that can cause rectal bleeding, bowel dysfunction, urinary incontinence and impotency.

The Hydrogel is a soft gel, injected into the area between the rectum wall and the prostate, a minimally invasive new procedure performed under local or general anaesthetic. The gel pushes the rectum about 1cm further away from the prostate and hence away from any potential damage from radiation. It stabilises the rectum and prostate against movement during treatment, with the hope of minimising harmful side effects.

It remains in place for three to six months, after which it is absorbed by the patient’s body and cleared in the patient’s urine. Permitted by NICE, but individual NHS Hospital Trusts are deciding whether to include the procedure within their treatment pathway, given that currently there is little good-quality evidence for this technique.

      Advantages and disadvantages of Radiotherapy

    • There is no incision, wound, anaesthetic, or recovery time.
    • Normal work can often be resumed after each treatment.

      But:

    • You must be prepared to travel each day to the centre.
    • Surgery is more difficult should radiotherapy fail, though HIFU is possible.
    • There are possible long-term side effects (see above and the section on Living with and Surviving Prostate Cancer).
    • Recognising recurrence is harder as there is no target PSA level.
    • Radiotherapy may be difficult after a bilateral hip replacement.