About this page. This is a plain English summary of radiotherapy for prostate cancer. It does not replace medical advice from your own doctor or specialist.
For full information and references, please read the detailed page.
What is radiotherapy?
Radiotherapy uses high-energy x-rays to damage cancer cells so they can no longer grow. For prostate cancer, it can be given in three main ways:
- External beam radiotherapy. A machine outside the body aims the beams at the prostate.
- High dose rate brachytherapy. Small radioactive sources are placed temporarily inside the prostate, then removed.
- Low dose rate (seed) brachytherapy. Tiny radioactive seeds are placed permanently into the prostate.
This page focuses on external beam radiotherapy, which is the most common form. Brachytherapy and seed therapy are covered on the detailed page.
What is external beam radiotherapy like?
External beam radiotherapy is given as an outpatient. You lie on a treatment couch while the machine aims focused beams at the prostate. Each session takes about 20 minutes, and on a standard course they are given Monday to Friday for around seven weeks.
Before treatment starts there is a planning session, usually with a CT scan (and sometimes an MRI), so the radiation can be shaped accurately to the prostate.
Most men can keep working through the treatment, although they often feel more tired than usual.
How long is a course of treatment?
Radiotherapy used to always be given over about seven to eight weeks. Large studies have since shown that giving a slightly higher dose at each visit over a shorter overall course (about four weeks) works just as well, so shorter courses are now common.
Some men are suitable for even shorter courses given in only a handful of sessions (sometimes called stereotactic radiotherapy or SBRT). Not every schedule suits every man - which one is right depends on the cancer and your situation, and the radiation oncologist will explain the options.
Side effects to expect
Some side effects are common in the short term, others can be longer lasting:
- Tiredness during and shortly after treatment is very common.
- Some men feel nauseous on occasion.
- Because the radiation passes near the bladder and the back passage, a smaller number of men have longer-lasting effects such as urinary urgency or frequency, bowel urgency or frequency, or rectal bleeding.
Protecting the back passage
The back passage (rectum) sits just behind the prostate, so it can receive some radiation. In some men a soft gel spacer is injected between the prostate and the rectum to push them apart and reduce the dose to the bowel, which can lower the chance of some bowel side effects. A spacer is not needed for everyone, and putting it in is a small procedure with its own minor risks - your team will advise whether it is worthwhile for you. (One such spacer is described in the patient brochures on the detailed page.)
Adding hormone therapy
For more aggressive cancers, radiotherapy is usually combined with about 12 months of hormone therapy. This improves the chance of controlling the cancer, but the hormone therapy itself has side effects (covered in the short version: hormone therapy).
An important trade-off with surgery
Surgery after radiotherapy is generally not possible. Radiation causes scarring inside the pelvis, which makes a subsequent operation very difficult.
Most large studies show that radiotherapy and surgery give similar results up to about 10 years. Beyond 10 years, the data is less clear-cut. For this reason, younger men or men with a long expected lifespan are often guided towards surgery, while radiotherapy is a strong option for older men, men whose cancer cannot be removed surgically, or men who prefer not to have an operation.
Dose and technique
Modern conformal radiotherapy can deliver a higher dose to the prostate while sparing more of the surrounding bladder and rectum. If radiotherapy is being recommended, it is reasonable to ask the radiation oncologist about the technique and dose they plan to use.
Radiotherapy after surgery
Radiotherapy is sometimes used after an operation to remove the prostate, if there is a higher risk of the cancer coming back. Rather than giving it to everyone straight after surgery, the usual approach now is to watch the PSA closely and give radiotherapy only if it starts to rise, so men who do not need it are not over-treated. The pathology results and PSA monitoring guide whether and when it is needed.
Follow-up: your PSA after radiotherapy
After radiotherapy the PSA is watched over time. Unlike after surgery, it does not drop straight away - it falls slowly to a low point and can wobble a little along the way, and a temporary rise (a "bounce") does not necessarily mean the cancer is back. This is why regular follow-up matters.
Important things to know
- Most men tolerate radiotherapy well, but a small percentage experience longer-lasting bowel and bladder problems. The detailed page references the relevant studies.
- If hormone therapy is added, the side effects of hormone therapy (hot flushes, lethargy, erection problems, bone thinning over time) need to be considered as well.
- Surgery is generally not an option after radiotherapy, so the order of treatments matters. Salvage treatments after radiotherapy are usually more limited.
- There is some evidence of a small increase in the risk of secondary cancers (such as bladder cancer) many years after radiotherapy, although this is contested.
- Radiotherapy is one of several effective treatments for prostate cancer. The right choice depends on the stage, grade, your age, and your preferences.
What you can do next
- Read the full detailed page with references.
- Short version: the full menu of treatment options.
- Short version: hormone therapy, often used alongside radiotherapy.
- Short version: robotic prostatectomy, the surgical alternative.
- Request a second opinion on a treatment plan.
- Call 02 8382 6980 to make an appointment.