Topical photodynamic therapy in the treatment of actinic keratoses and Bowen’s disease in transplant recipients

Background. Transplant recipients (TR) have a dramatically increased risk for widespread epithelial neoplasms of the skin. Thus, there is a need to treat initial stages of these neoplasms such as actinic keratoses (AK) and Bowen's disease (BD) to prevent progression to invasive and potentially fatal squamous cell carcinoma. Topical photodynamic therapy (PDT) has been proven to be an effective treatment for AK and BD in immunocompetent patients, but no prospective trials in immunocompromised TR have been performed so far. Methods. Twenty TR and 20 controls with histologically confirmed AK or BD underwent either a single or two consecutive treatments of topical PDT in an open trial. The application of 20% 5-aminolevulinic acid (ALA) for 5 hours was followed by illumination with 75 J/cm 2 of visible light delivered at 80 mW/cm 2 by an incoherent light source. Results. The overall complete response rates in TR at 4, 12, and 48 weeks were 0.86, 0.68, and 0.48, respectively. The cure rates in both patient groups were comparable at 4 weeks but were significantly lower in TR than in controls at 12 and 48 weeks (P<0.05). Side effects included erythema, edema, and crust formation after illumination. Cosmetic results were excellent without scar formation or alterations in pigmentation. Conclusions. Topical PDT with 20% 5-ALA is an effective and safe treatment for AK and BD in immuno-suppressed TR, with initial response rates comparable with those in immunocompetent patients. It is particularly useful in TR because of the possibility for repeated treatment of large lesional areas.