Photodynamic Therapy (PDT) has been used to treat cancer for more than 25 years on surface or superficial lesions, such as skin cancer. It is now being tested as a new treatment for organ-confined prostate cancer at University College London. PDT is also called Vascular-Targeted Photodynamic therapy (VTP).
PDT uses a drug, called a photo-sensitiser, which is injected into the bloodstream of the patient under general anaesthetic. Within a few minutes, the drug circulates into all the patient’s cells. An ultrasound probe is put into the patient’s back passage, so that the prostate can be seen on a monitor screen. A template (a rectangular grid with holes in it) is placed on the patient’s skin behind the scrotum.
Thin, hollow needles are then pushed through the template into the prostate. The needles can be seen on the ultrasound monitor and their position can be adjusted if necessary. Once the needles are in the right position, optical fibres can be passed through the needles. Low powered laser light is shone through the fibres, activating the light-sensitive drug. The drug causes damage to the cell walls, which has the effect of starving the cells of blood, causing cell death.
The operation lasts about 2 - 3 hours. Patients need to stay out of bright light for the next 24 – 48 hours.
Note: It is far too early to know whether PDT could be as effective as other treatments for prostate cancer. It is not approved as an NHS treatment.