A comparative analysis of Mohs micrographic surgery with or without photodynamic therapy for locally advanced basal cell carcinoma.

Background: Locally advanced basal cell carcinoma (laBCC) is a more severe subtype of BCC, characterized by large, deeply invasive tumors that often occur in cosmetically or functionally sensitive areas. Mohs micrographic surgery (MMS) is the standard treatment, offering high cure rates through layer-by-layer excision with microscopic margin control. However, MMS alone may not entirely prevent recurrence in aggressive or infiltrative subtypes. Photodynamic therapy (PDT) is a non-invasive treatment modality that may enhance outcomes when used adjunctively. This study evaluated whether combining MMS with PDT offers advantages over MMS alone for laBCC.

Method: A retrospective cohort study was conducted with 63 patients diagnosed with laBCC, categorized by histological subtype into aggressive and non-aggressive groups. Patients were not randomized; they received either MMS alone or MMS followed by PDT based on clinical decision-making at treatment time. Clinical outcomes were analyzed, including recurrence, recurrence-free survival (RFS), and surgical margins.

Results: MMS group exhibited a low recurrence rate of 4.4 %, against 22.2 % for MMS+PDT group. Non-aggressive tumours such as superficial, nodular, and adenoid types, treated with MMS and PDT had a 16.7 % recurrence rate, compared to 25 % for aggressive tumours, including Infiltrating, Basosquamous, and morphea form types. This suggests that non-aggressive cases may respond better to PDT. Additionally, the mean recurrence-free survival(mRFS) time was about 54 months (95 % CI: 50- 57.3 months) for non-aggressive tumours, while aggressive tumours had a mean survival of 52.3 months (95 % CI: 51-56.2 months), indicating a potential trend favouring non-aggressive tumours.

Conclusion: MMS combined with PDT show favourable outcomes in non-aggressive BBC.