There are a number of reasons why surgery is not usually possible after a course of radiotherapy for prostate cancer. These include:

• if a cancer comes back in the prostate after radiotherapy treatment it is very likely that the growth will have spread to involve other organs which lie very close to the gland, including the bladder and the rectum (bowel). Even if there are only microscopic traces of cancer invading these organs they will still have to be removed, along with the prostate gland and surrounding tissues, to ensure the cancer is completely cleared. This would involve a very major operation which is not normally possible.
• when radiotherapy is given for an early prostate cancer a high dose of radiation is used in order to try and destroy the tumour completely. However carefully the radiotherapy is planned and carried out this does mean that some of the normal tissues around the prostate gland will get quite a high dose of radiation. This will lead to scarring and some reduction in the blood supply of some of these tissues. Usually this does not cause any significant problems or symptoms but it does mean that operating on these tissues at a later date can be very difficult with a much higher risk of serious complications. Therefore further surgery is usually best avoided.
• if a cancer has come back in the prostate gland after radiotherapy there is a strong likelihood that it will have sent seedlings of tumour in the blood stream to other parts of the body, particularly to the bones. Although these seedlings may be microscopic and causing no problems the fact that the cancer has spread elsewhere does mean that a major operation to remove the prostate gland will still not cure the condition and so would not be beneficial.

Surgery is occasionally possible for a local relapse after radiotherapy, particularly where there is a small recurrence of a low grade cancer, but in practice less than one in twenty prostate cancers are suitable for surgery after radiotherapy.

One or more of these may have been factors leading your doctors to decide it was best not to recommend surgery to you but, for your own peace of mind, it would be a good idea to discuss with them precisely why they made their decision.