A split-face comparison of photodynamic therapy using blue light versus intense pulsed light for treatment of facial actinic keratosis

Actinic keratosis (AK) is a UV-induced, pre-cancerous lesion that can progress to squamous cell carcinoma (SCC). P53 is found to be mutated in UV-induced skin cancer. As a result, its protein level is increased and can be detected by immunohistochemical analysis (IHC). The level also increases as the degree of severity of keratinocytes atypicality increases.;Photodynamic therapy (PDT) uses 20% 5-aminolevulinic acid (5-ALA) and blue light and has been approved for facial AK treatment. The use of short-contact, full-face therapy is now considered to be the standard of care. Significant clinical clearance of facial AK also has been shown when using other light sources, including intense pulsed light (IPL). Despite the growing data on both modalities, a study on the impact of p53 expression has not yet been conducted.;Objective: 1) to compare the efficacy of short incubation ALA-PDT-IPL, both clinically and histologically, with short incubation ALA-PDT-Blu-U and 2) to study the impact of short-incubation PDT on p53 expression in AK.;Design: A split-face comparison study of short-incubation 5-ALA-PDT using blue light vs. intense pulsed light (IPL) in the treatment of facial AKs.;Patients: 6 patients ranging from 66 to 72 years old with facial AKs.;Intervention: One-hour incubation of 5-ALA followed by blue light exposure to one half of the face, and IPL to the other half. 2 sessions were done at 4 week intervals. Biopsy specimens of AKs were taken from each side of the face 2 weeks before and 4 weeks after the intervention.;Outcome Measurement: Clinical AK clearance, histological severity of AK, and level of p53 expression using IHC were assessed pre- and post-treatment in both modalities. Adverse reaction (AR) of PDT were also assessed and compared. This included pain during the treatment and phototoxic reactions.;Results: 6/6 patients had 100% clinical clearance rate on both sides (P = 0.0005, 95% C.I. (3.49, 6.85)). The histological severity of AK on the IPL-treated side was significantly improved (P = 0.0028, 95% C.I. (0.92, 2.28)). The severity on the Blu-U treated side was also improved but not significantly (P = 0.0705, 95% C.I. (-0.16, 2.56)). There was a significant decrease in the level of p53 expression on both the IPL-treated side (P = 0.0259) and Blu-U treated side (P = 0.0121).;As for AR, the severity of pain during the treatment and phototoxic reaction after PDT were generally mild on both sides.;Conclusions: IPL can be confidently used as a light source in short-incubation 5-ALA-PDT. It provides significant clinical clearance and histological improvement of facial AK with mild AR. Short-incubation PDT decreases the level of p53 significantly which reflects the improvement in atypicality of keratinocytes. High-risk patients can have longer skin cancer-free intervals and decrease the risk of having a new lesion with good sun protection. Further studies are needed in order to confirm these results.