Photodynamic therapy (PDT) is a modern treatment for certain types of non-melanoma
skin cancer (NMSC) as well as pre cancerous skin lesions. Dr Murdoch has been treating
skin cancer patient’s with PDT since 2001, soon after the light sources for this
treatment became commercially available in the UK.
The treatment consists of applying methyl aminolevulinate (MAL or Metvix) cream to
the skin lesion and 3 hours later, shining a pure red light on it. During the three
hour period the methyl aminolevulinate in the cream is metabolised by skin cancer
cells to produce a chemical called protoporphyrin IX (PPIX). The PPIX interacts with
the red light and the body’s own oxygen to selectively kill the skin cancer sells.
During the light treatments which lasts around 8 minutes a stinging or burning sensation
can be felt but for most patient’s this is easily tolerated. If the stinging sensation
is too strong a local anaesthetic injection can be used. By itself the red light
is harmless and causes no sensation on the skin.
PDT offers a non surgical alternative
treatment for skin lesions. The number of PDT treatments will be dependent on the
type of lesion that is being treated. Actinic keratoses usually require a single
treatment of PDT but basal cell carcinomas and Bowen’s disease require two treatments
one week apart.