Photodynamic therapy was first utilized at Roswell Park in Buffalo, New York with photopherin in the late 1980's. A Canadian group started using used aminolevulinic acid (ALA) in 1990. Oslo University Hospital started development with photopherin and ALA in 1991 and later developed a sensitizing cream based on an ester derivative of ALA which is marketed under the name Metvix®.
Metvix® is a cream containing methylaminolevulinic acid. In cells, this is metabolized to protoporphyrin IX through heme synthesis. Neoplastic tissue breaks down protoporphyrin IX quicker than healthy tissue, which leads to a difference in the concentration of the light-sensitive protoporphyrin IX. When the cells are exposed to the red portion of the light spectrum, a singlet oxygen is created which damages cell mitochondria and cell membranes leading to cell death. This selective effect depends on cream being absorbed into the neoplastic cells, that the difference in the concentration of protoporphyrin IX is great between the healthy and neoplastic cells, and that a sufficient dose of light reaches the tissue.
Both preparation and application of the cream are associated with pain to a varying degree, depending on size, location on the body, and the patient's pain tolerance.
Images of patient before and after treatment:
- Superficial and/or nodular basal cell carcinoma
- Actinic keratoses with squamous cell atypia, possibly in situ or Bowen's disease
- Cure the disease and achieve the best possible cosmetic result.