History:

Photodynamic therapy has recently been licensed in Australia for the treatment of superficial basal cell skin cancers and solar keratoses using Metvix ointment and an activating light source, usually a red light.  Metvix does not penetrate deeply into the skin.  It only penetrates a couple of millimetres.  This means that only superficial skin cancers are suitable for treatment with photodynamic therapy.  Red light is one of the longer wavelengths of light and therefore it will penetrate deeply enough to activate any Metvix that has penetrated into the skin and into a superficial skin cancer.  The physical characteristics of both the penetration and the light dictate the thickness of lesions that can be treated.

  It is important to note that infiltrating, recurrent,sclerotic or morphoeic basal cell skin cancers, micronodular basal cell skin cancers or basi-squamous cell skin cancers are not suitable for photodynamic therapy. 

 Examples of these unsuitable skin cancers are shown in the pictures above. 

 

The technique of Photodynamic therapy is shown here   Before photodynamic therapy is carried out on a lesion a biopsy should be taken unless you are a specialist dermatologist who is completely confident with his clinical diagnosis.  It is salutary to note that specialist dermatologists are often only correct 75% of the time in differentiating superficial basal and superficial squamous cell skin cancers.  Superficial squamous cell skin cancers in hair bearing areas often penetrate down the hair follicle and these areas will not be reached by the Metvix cream and hence photodynamic therapy will not be successful. 

Click here for other images of Basal Cell skin cancer in Globalskinatlas.