Bowen's disease, solar keratoses and superficial basal cell carcinomas treated by photodynamic therapy using a large-field incoherent light source.

Abstract

Photodynamic therapy (PDT) has not yet been demonstrated to be superior to conventional treatment in the treatment of superficial skin cancers and premalignant skin conditions. A limitation for PDT is the absence to date of a light source suitable for the treatment of larger lesions or 'field changes' where several lesions are present on one anatomical site. To investigate the safety and efficacy of a large field light source, the Waldmann PDT 1200, in the treatment of Bowen's disease (BD), superficial basal cell carcinomas (BCCs) and solar keratoses (SKs). After application of 5-aminolaevulinic acid for 4-6 h, each lesion was irradiated with 105 J cm-2 of incoherent red light centred on 640 nm. Eighty-eight patients with 239 lesions were recruited. Within two treatments, 88% of BD lesions, 95% of BCCs and 99% of SKs showed complete clinical clearance. At 12 months the complete response rates were 69% for BD, 82% for BCC and 72% for SK. This study confirms that PDT is a useful treatment and that selected superficial BCCs and SKs respond well to PDT. The PDT 1200 light source proved capable of treating multiple lesions amounting to a 'field change' and also lesions up to 10 cm in diameter within an acceptable treatment time. Thus far, PDT has failed to become established as a routine treatment for small premalignant and malignant skin lesions as it has not proved superior to simple cheaper conventional therapies such as cryotherapy, curettage and cautery, topical chemotherapy with 5-fluorouracil, or surgery. However, PDT has become established as a treatment for selected cases in some centres. This study suggests a role for PDT in the treatment of large premalignancies, superficial BCCs and field change where existing treatments may be problematic.