Investigation of the use of the pulsed dye laser in the treatment of Bowen's disease using 5-aminolaevulinic acid phototherapy.

Background: The use of 5-aminolaevulinic acid photodynamic therapy (ALA-PDT) for the treatment of Bowen's disease is well established. However, treatment with a continuous light source has the disadvantage of prolonged treatment time during which patients often experience significant discomfort requiring the use of local anaesthetic.

Objectives: The aim of this study was to assess the efficacy and safety of the pulsed dye laser (PDL) as the light source for photoactivation of the protoporphyrin IX to treat Bowen's disease by PDT.

Methods: Thirteen patients with a total of 17 patches of histologically proven Bowen's disease were treated with 20% 5-ALA in Unguentum M (Crookes Healthcare, Nottingham, U.K.) under occlusion for 4 h. The patches were then irradiated using a Candela SPLTL-1b (Candela Corporation, Wayland, MA, U.S.A.) PDL using a wavelength of 585 nm, with a 7-mm diameter spot at a fluence of 10 J cm(-2). The spots overlapped by 50% to cover the lesion and extend beyond the clinical margin of the patch of Bowen's disease by 0.5 cm. Patients were then followed up initially at 2 months, then at 3-monthly intervals for a period of 12 months to assess treatment success and recurrence rate.

Results: Subjects consisted of 10 females and three males, between 47 and 88 years. The mean area of the patches of Bowen's disease was 315.4 mm(2) (range 36-2464 mm(2)) requiring a median of 32 pulses (range 3-260). Lesions sites were hands (two), foot (one) and lower leg (14). All patients experienced varying degrees of discomfort during treatment but none required the use of local anaesthetic. At 2 months eight treatment sites could not be assessed due to loose overlying crusts and removal of these revealed superficial erosions in seven patients. Of the 17 lesions treated, on follow-up at 1 year, 14 patches (82%) demonstrated a complete clinical response, although one of these had required a second treatment. Two patients with three lesions that would have required further therapy refused a second treatment. Prolonged crusting lasting 8 weeks occurred in eight patches and prolonged discomfort lasting 6 weeks occurred in four patients.

Conclusions: This study has shown that the PDL is an effective light source for ALA-PDT of Bowen's disease. Light source exposure times are shorter, although overall treatment time may not always be significantly reduced for larger lesions. The procedure was well tolerated. However, the post-treatment morbidity was relatively high compared with the more conventional treatment modalities. Further studies are needed to determine whether lower energy fluences can maintain similar efficacy while reducing post-treatment morbidity.