Toxicities and early outcomes in a phase 1 trial of photodynamic therapy for premalignant and early stage head and neck tumors

•Treating severe dysplasia, carcinoma in situ, and early head and neck cancers is challenging.•Treatment with photodynamic therapy with Levulan allows for relatively short-term light precautions.•Maximum Tolerable Dose has not been reached in our phase 1 study.•It is too early to suggest a dose response for light doses in our study.•We find high marginal recurrence rates, suggesting use of generous light fields.