Treatment efficiency of combining photodynamic therapy and ionizing radiation for Bowen’s disease

Background Topical 5‐aminolevulinic acid photodynamic therapy (ALA‐PDT) is widely used for treating Bowen’s disease (BD), but recurrence and tumour cell persistence after ALA‐PDT is sometimes problematic. Radiation therapy (RT) is also effective for BD, but is limited by its side‐effects, such as refractory ulcers. Objective The objective of the study was to observe a synergic effect of combination therapy with ALA‐PDT and RT for BD cases that did not respond effectively to prior ALA‐PDT. Methods Subjects were BD patients whose lesion did not show complete remission or showed recurrence after prior ALA‐PDT. A total of four cases involving four lesions were studied (three male and one female, mean age 69.5). ALA ointment (20%) was applied to the lesions. After 4 to 6 h, subjects received combination therapy consisting of excimer‐pumped dye laser radiation at 630 nm (50 J/cm²) followed by electron‐beam radiation (3 Gy). The combination therapy was repeated every 2 to 3 days for a total of four treatments. The lesions were evaluated clinically or histologically after the final combination therapy session. Results Following combination therapy, all of the lesions disappeared. Recurrence was not detected during the observations periods, which averaged 14.0 months in duration. Conclusion Our results indicate that the cure rate of BD could be improved by combination therapy with ALA‐PDT and RT. Compared with conventional RT, the synergetic effect of this therapy might reduce the dose of radiation required, thereby also reducing skin side‐effects such as refractory ulcers.