Photodynamic therapy (PDT)
In photodynamic therapy, a light-activatable active substance makes diseased skin cells sensitive to red light; the subsequent illumination damages these cells. The method is used for actinic keratoses and other superficial forms and precursors of non-melanoma skin cancer.
Overview
Photodynamic therapy (PDT) is a light-based method for treating precursors and superficial forms of non-melanoma skin cancer. A cream containing a light-activatable active substance is applied to the affected skin areas. It is taken up above all by the diseased cells and converted there into protoporphyrin IX, a substance that makes the cells highly sensitive to red light. When the area is then illuminated, the enriched cells are damaged; the surrounding healthy tissue takes up considerably less of the active substance.
Two variants are available for the illumination. In classic PDT the cream is first left to act for a few hours under a light-proof dressing; the area is then illuminated with cold red light at a wavelength of around 634 nanometres [PLATZHALTER: Gerätemodell bestätigen]. In daylight PDT the cream acts for about 30 minutes; this is followed by a two-hour illumination with light of the visible spectrum from 400 to 750 nanometres from special LED lamps [PLATZHALTER: Gerätemodell bestätigen]. This variant is usually considerably less painful, but the illumination takes considerably longer.
PDT is used for actinic keratoses, Bowen's disease and superficial basal cell carcinomas. It can also treat larger, widespread areas in a single session. How the treatment proceeds in detail, which side effects to expect, where the limits of the method lie and which alternatives exist is described on the page on actinic keratoses. In actinic keratoses on heavily sun-damaged skin, PDT can be combined with the fractional CO₂ laser; whether that makes sense in an individual case depends on the findings.
Areas of application
- Actinic keratoses, single or widespread (field cancerisation)
- Bowen's disease
- Superficial basal cell carcinomas after medical assessment