EFFECT OF PHOTODYNAMIC THERAPY ON THE HEALING OF A RAT SKIN FLAP AND ITS IMPLICATION FOR HEAD AND NECK RECONSTRUCTIVE SURGERY

Background and Objective: Photodynamic therapy (PDT) may as adjuvant t herapy be used to reduce tumor recurrence in the head and neck with su rgery, given intraoperatively after resection. A concern with the use of intraoperative PDT is the possible effect on wound healing, especia lly on the healing of myocutaneous skin flaps, which are widely used t o reconstruct defects following resections for head and neck cancer. S tudy Design/Materials and Methods: A flap, based on the inferior epiga stric artery, was prepared in thirty male Lewis rats. Group I did not receive any further treatment but the wound was left open for 20 minut es. Group II was injected with 5mg/kg Photofrin, 48 hours prior to the operation and also did not receive any further treatment. The wound b ed and wound borders of group III were treated with 630nm light of dif ferent dosages, delivered by an argon dye laser. Animals in group IV r eceived 5mg/kg Photofrin 48 hours prior to the operation and their wou nd beds were treated with the same light dosages as group III. After t he treatment all flaps were replaced into the wound bed and the incisi ons were closed. Biopsies for histological analysis were taken at seve ral time points; and on day 21, biopsies for wound tensile strength me asurements were taken. Results: The wound healing in group I, II, and III appeared normal and there were no differences seen between these g roups. Also, the tensile strength did not differ significantly. The fl aps of group IV showed serous effusion, epidermal necrosis, and weaker tensile strength (P = .04 and .02 for the light doses of 50 J/sq cm a nd 75 J/sq cm respectively) at a specific time point. Conclusion: The results of this study demonstrate that PDT given immediately before fl ap reconstruction will result in delayed wound healing. These results should be considered when contemplating the use of PDT as adjuvant int raoperative therapy for tumor surgery requiring flap reconstruction af ter ablative surgery. (C) 1996 Wiley-Liss, Inc.