Photodynamic therapy with topical methyl aminolaevulinate for 'difficult-to-treat' basal cell carcinoma

Background Basal cell carcinoma (BCC) may be difficult to treat by conventional means, particularly if the lesions are large or located in the mid-face (H-zone). Photodynamic therapy (PDT) using topical methyl aminolaevulinate (MAL) may be a good noninvasive option for these patients. Objectives To investigate the efficacy and safety of PDT using MAL for BCCs defined as 'difficult to treat', i.e. large lesions, in the H-zone, or in patients at high risk of surgical complications. Methods This was a prospective, multicentre, noncomparative study. Patients were assessed 3, 12 and 24 months after the last PDT treatment. One hundred and two patients with 'difficult-to-treat' BCC were treated with MAL PDT, using 160 mg g(-1) cream and 75 J cm(-2) red light (570-670 nm), after lesion preparation and 3 h of cream exposure. Results Ninety-five patients with 148 lesions were included in the per protocol analysis. The histologically confirmed lesion complete response rate at 3 months was 89% (131 of 148). At 12 months, 10 lesions had reappeared, and therefore the cumulative treatment failure rate was 18% (27 of 148). At 24 months, an additional nine lesions had reappeared, resulting in a cumulative treatment failure rate of 24% (36 of 148). The estimated sustained lesion complete response rate (assessed using a time-to-event approach) was 90% at 3 months, 84% at 12 months and 78% at 24 months. Overall cosmetic outcome was judged as excellent or good in 79% and 84% of the patients at 12 and 24 months, respectively. Follow-up is continuing for up to 5 years. Conclusions MAL PDT is an attractive option for 'difficult-to-treat' BCC. Because of the excellent cosmetic results, the treatment is particularly well suited for lesions that would otherwise require extensive surgical procedures.