Newer therapies currently being evaluated include photodynamic therapy (PDT), high-intensity focused ultrasound (HIFU) and cryosurgery.
Photodynamic therapy (PDT)
PDT is based on the concept that light sources, combined with a light sensitive drug (sometimes called a photosensitising agent) can destroy cancer cells. PDT seems to have a potential in the treatment of prostate cancer however, currently this is regarded as an experimental treatment and definitive information will only be available with the conclusion of clinical studies and the reporting of long-term results (43).
High-intensity focused ultrasound (HIFU)
HIFU is a method of focusing ultrasound waves on a particular area to create heat in the tissues. This heat can result in tissue death due to coagulative necrosis. Results obtained in a Phase II/III prospective multi centre clinical trial (44) looking at 402 patients, confirmed that HIFU is an option to be considered for the primary treatment of selected patients with localised prostate cancer. Longer follow-up is required. Long term outcome data, and good quality evidence of the toxicity profile are lacking.
Cryosurgery
Cryosurgery, or cryoablation, uses liquid nitrogen to produce temperatures of -50°C or lower in the tumour tissue. The liquid nitrogen is circulated through an instrument called a cryoprobe which can be placed in or up against the cancer. The role of cryotherapy in the treatment of prostate cancer is still being explored (45).
Early indications are that it may be a viable alternative to surgery or radiotherapy, but it cannot currently be recommended as long-term data is still lacking. It is not suitable for larger tumours, those which have broken through the capsule surrounding the prostate gland or for men whose cancers have spread beyond the prostate.