Photodynamic therapy (PDT) uses certain wavelengths of light to treat cancer tumours (basal cell carcinomas) and precancerous lesions (actinic keratoses, Bowen’s disease). For this purpose, a photosensitizing cream is rubbed into the tumour tissue, which is then exposed to light. The combination of light and photosensitizer destroys the tumour cells. PDT is a tissue-conserving procedure which doesn’t distress the patient. The cosmetic results are usually excellent.