Photodynamic therapy for basal cell carcinoma: clinical and pathological determinants of response

Background Photodynamic therapy (PDT) is increasingly used in the treatment of basal cell carcinoma (BCC). However, scant information is available about the impact of both patient-and lesion-related characteristics on the effectiveness of therapy. Therefore, on the basis of the current data, it is difficult to draw clear-cut indications to use PDT for treatment of BCC in clinical practice. Objective To investigate the clinical and pathological determinants of response of BCC to PDT with methylaminolevulinate (MAL) and red light. Methods The clinical and pathological characteristics of 194 BCCs in 135 patients, treated with MAL-PDT, were evaluated. Lesions were treated with MAL-PDT according to established methods and the response was assessed by clinical follow-up of the patients. Results Complete response to PDT was 62%, with a better response for superficial BCC (95 /116, 82%) than nodular BCC (26 /78, 33%). When determinants of response were analysed, the nodular type and the location on the limbs emerged as significant clinical predictors of failure. Among the pathological characteristics, the nodular and infiltrative histotypes, as well as ulceration and tumour thickness were associated with a lower response to therapy. Patients' age and gender, as well as the size of the lesions, were not found to be significant predictors. Conclusions Optimization of PDT procedure for BCC requires a careful selection of the lesions. In particular, superficial BCCs, preferentially located on the trunk, show the best therapeutic response.