Long-term effect of photodynamic therapy on oral squamous cell carcinoma and epithelial dysplasia

•PDT for oral squamous cell carcinoma and epithelium dysplasia provides reliable short-term outcomes, but its long-term effects are limited.•When PDT is applied to oral squamous cell carcinoma, long-term follow-up is essential because of the high risk of recurrence.•New therapies will need to be developed to acquire the reliable outcome in the future. Oral squamous cell carcinoma (OSCC) treatment consists mainly of surgery, chemotherapy, and radiotherapy, alone or in combination. Epithelial dysplasia (ED) is also treated with surgery. However, these treatments can induce functional and/or aesthetic disturbances. Photodynamic therapy (PDT) can preserve organs. Although short-term studies have shown good progress, long-term evaluations have not yet been conducted. This study aimed to clarify the long-term effects of PDT on OSCC and ED. Methods: Patients who underwent PDT with the first (porfimer sodium) or second generation photosensitizers (talaporfin sodium) for early OSCC (T1 and T2) and ED were included in this study. The long-term prognosis was assessed. Twenty-three patients were included. Complete response (CR) was observed in 19 patients (82.6%) and partial response (PR) in 4 patients (17.4%) 4 weeks after PDT. Regarding long-term progress, local region recurrence occurred in 11 of 19 CR cases (57.9%), and the term of recurrence was 27.4 ± 30.4 months. Surgical resection was performed in all local recurrence and PR cases, and 3 patients died of the underlying disease. PDT provides a good outcome in the short term, but its long-term effects are limited.