External Beam Radiotherapy
This treatment uses a method called conformal radiotherapy. This allows the radiotherapist to follow the shape of the prostate in three dimensions and to target the prostate while limiting damage to surrounding tissues.
Intensity modulated radiotherapy (IMRT) uses technology to follow the contours of the prostate to deliver higher, more targeted doses of radiation to increase its effectiveness while reducing unwanted side effects.
Image guided radiotherapy (IGRT) is a common technique used to assist radiation targeting and involves placing three (non-radioactive) seeds into the prostate before treatment.
This means the doctor can better monitor the position of the prostate during the course of radiotherapy.
External beam radiotherapy is usually divided into small doses over some weeks (e.g. a few minutes of treatment on each of 5 days per week over 7–8 weeks).
Radiotherapy is a suitable treatment for men with low to high risk prostate cancer. It does not have a sudden stressful impact on the body as surgery does and so is appropriate for older people and those with other illnesses and who are not strong enough to undergo surgery. It is also useful to treat disease that has spread just outside the prostate, but is contained within the prostate region.
Side effects are different from surgery. Temporary bowel problems such as diarrhoea and bladder irritation (cystitis) occur in most men after radiotherapy but usually settle down in time. Some men may experience long term diarrhoea, however the incidence of severe, permanent urinary or bowel side effects is low (1–2%). Side effects of radiotherapy may be minimal initially but can increase over several years after treatment. In an Australian study, at 3 years, urine leakage occurred in 3% of men, 2 men out of 3 were impotent and 15% had bowel problems(1).
External beam radiotherapy alone is a successful treatment for men with low and intermediate risk cancer. For men with high risk cancer, it may be combined with hormone therapy (also called androgen deprivation treatment) to improve cancer control.
Brachytherapy involves introducing permanent radioactive seeds (low dose rate) or temporary wires (high dose rate) into the prostate. The latter may be delivered with a 4-week course of external beam radiation.
Low dose rate (LDR) brachytherapy
LDR is offered to men with low risk cancer: a small, slow-growing tumour and a PSA less than 10 ng/mL. Control of the cancer is comparable to external beam radiotherapy and surgery.
Erectile problems are usually fewer after LDR brachytherapy than after surgery, with 36% impotent at 3 years in the Australian study quoted earlier(1). Brachytherapy may have a greater risk of troublesome urinary symptoms (poor stream, frequent urination, etc.) than either surgery or external beam radiotherapy. For this reason, men’s lower urinary tract symptoms are assessed before this treatment is offered. There is a small risk of urinary retention (inability to urinate) and some men may need to wear a urinary catheter initially. Bowel problems were not experienced by men undergoing LDR brachytherapy in the Australian study (1).
High dose rate (HDR) brachytherapy
HDR can be used to deliver very high doses of radiation to the prostate. It involves the temporary insertion of needles with the radioactive source on two to four occasions. It is often supplemented with EBRT. This treatment is suitable for men with intermediate and high risk cancers.
Side effects are similar to other forms of radiotherapy, although erectile problems are higher than after LDR brachytherapy (72% impotence in the Australian study (1)).
1. Smith DP, et al. Quality of life three years after diagnosis of localised prostate cancer: population based cohort study. British Medical Journal 2009;339(2):4817.