Many experts believe that radiotherapy should be offered to patients with locally advanced disease, usually in combination with hormonal therapy.(6),(7) Combining it with hormonal therapy may improve survival.
The immediate and long terms side effects of radiotherapy are well known. Before having radiotherapy patients should be counselled about the risks of bowel/bladder damage, impotence and infertility. Impotence may occur in between 30% and 50% of patients (depending on age). Because of the potential for bowel damage, radiotherapy is contraindicated in men with a history of inflammatory bowel disease.
Sperm banking should be offered as an option to men for whom loss of fertility is an issue.
There are still uncertainties associated with radical radiotherapy about the optimum dose and field size (particularly to the extent treatment includes pelvic lymph nodes).(8) About a quarter of men with T3 disease will have occult nodal metastases.
The RTOG 9413 trial showed some benefit in progression free survival for patients treated with whole pelvis radiotherapy and neo-adjuvant hormonal therapy.(9) So, there may be some benefit in treating the regional lymph although this hasn't yet been demonstrated.
There are two ways of giving external beam radiotherapy (EBRT): conformal radiotherapy and intensity modulated radiotherapy (IMRT).
Conformal radiotherapy
Conformal radiotherapy (CRT) is progressively taking over from external beam radiotherapy as the standard method of treatment. CRT uses a linear accelerator machine in a similar way to conventional EBRT, but involves three dimensional planning and delivery to match the radiation to the size and shape of the prostate. This ensures that the radiation dose is primarily given to the tumour. Healthy surrounding cells and nearby structures receive a lower dose of radiation. This can help to reduce the risk of side effects.
Using conformal radiotherapy, higher doses of radiation can be used, than are used in conventional EBRT. High-dose conformal therapy has been shown to reduce the risk of recurrence without increasing the risk of urinary and rectal side effects.(10)
Intensity modulated radiotherapy (IMRT)
Intensity modulated radiation therapy is a specialised form of conformal radiation therapy and isn’t widely available across the UK. The radiation can be adjusted to vary the doses given to the prostate and surrounding structures. This allows a higher dose to be given to the prostate and lymph nodes while normal tissue is exposed to a lower dose. A reduction in the amount of radiation that the bowel and bladder receive can help reduce local damage and side effects. But currently there is no evidence to confirm that IMRT is a more effective form of radiation treatment.
The acute and late toxicities of high-dose radiation using conformal radiotherapy and intensity modulated radiation therapy have been compared in a study that reported in 2000.(11) Acute and late urinary toxicities were not significantly different for the two methods. However, the combined rates of acute grade 1 and 2 rectal toxicities and the risk of late grade 2 rectal bleeding were lower in the IMRT patients. Unfortunately this study is not conclusive and the full effectiveness of IMRT is unknown at present.
Another type of radiotherapy which is being used increasingly for the treatment of early prostate cancer is brachytherapy. It involves radioactive sources being implanted directly into the prostate gland. This approach is not generally suitable for men with locally advanced disease unless it’s combined with external beam radiotherapy to give a high-dose boost to the prostate.