ISSUE
44
December 2010
Radiation therapy and prostate cancer Radiation therapy or radiotherapy is a widely used and effective treatment for prostate cancer. In general terms, all radiation therapy techniques use some form of high energy or ‘ionising’ radiation to cause damage to the cancer. By interfering with the way enough of the cancer cells grow or multiply, radiation therapy can reduce or eliminate the cancer.
Brachytherapy is another well known form of radiation therapy for prostate cancer where an implant is placed in the prostate to deliver the radiation directly within it. Like EBRT, it can be given in a few different ways. A permanent implant uses small radioactive pellets, about the size of a grain of rice, which deliver a gradual dose of radiation (over about six months) to an area of just a few millimetres. By placing a large number of these throughout the prostate under anaesthetic, a substantial dose of radiation can be effectively delivered to the cancer, with only a small amount to the surrounding areas. This is called low-dose-rate or LDR brachytherapy.
Radiotherapy can be used to treat cancers within the prostate to try to cure it, as well as being very useful for suppressing complications of cancer which has spread to other parts of the body. It is typically delivered using a machine called a linear accelerator which produces a beam of high energy x-rays; this is called external beam radiotherapy (EBRT). Modern linear accelerators range from the standard large machine which has a beam that can move slowly around the patient, to accelerator heads built into machines similar to CT scanners or on robotic arms.
Alternatively, a temporary high-dose-rate or HDR brachytherapy treatment can be delivered in hospital over 24 hours. Under anaesthetic, up to 20 needles are inserted into the prostate to deliver small, highly intense radiation for a short duration. In most cases, this is done with two or three large radiation doses during the one implant session. After the treatment, all the needles are removed and no radioactivity remains within the patient. HDR is often supplemented with EBRT, where its effect is equivalent to more than four weeks of EBRT alone and so it halves the duration of a typical EBRT course. CONTINUED PAGE 3