Topical application of photofrin for photodynamic diagnosis of oral neoplasms

Background: The prognosis of patients with oral cancer can be improved by early diagnosis. Exact demarcation of tumor margins could contribute to optimum results in surgical excision and reconstruction. Therefore, the purpose of this study was to evaluate Photofrin (Quadra Logic Technologics, Inc., Vancouver, British Columbia, Canada) with protoporphyrin IX fluorescence as a new diagnostic procedure: photodynamic diagnosis for the detection of hyperplastic and malignant changes in oral tissue. Methods: Twenty patients with oral neoplasms received 2.5 mg/ml Photofrin solution topically. After a period of 3 hours, the patients underwent fluorescence illumination (λex = 370 to 450 nm). Guided by their visible fluorescence, lesions were biopsied at four suspicious sites for each patient. All specimens were analyzed and measured by a pathologist. A quantitative analysis of the fluorescence contrast between the neoplastic and healthy tissue was performed using the red, green, and blue mode and the gray scale mode. Statistical analysis was performed by means of the analysis of variance test for multiple comparisons. Results: The sensitivity of the neoplastic tissue evaluated using the red, green, and blue and the gray scale modes combined was 92.45 percent in the macroscopic study and 93.75 percent in the microscopic study. The specificity of the neoplastic tissue evaluated using the red, green, and blue and gray scale modes combined was 95.65 percent in the macroscopic study and 97.50 percent in the microscopic study. Five patients (25 percent) displayed hyperkeratosis, nine (45 percent) displayed squamous hyperplasia, and six (30 percent) displayed squamous cell carcinoma. It is likely that Photofrin induced the visible red fluorescence. Some fluorescence could be detected in the surrounding healthy tissue. The intensity of the light was much lower than that from the lesions. The difference between healthy tissue and the lesions as a group was statistically significant. Conclusions: Light-induced fluorescence detection using topical Photofrin provides a sensitive, noninvasive technique for the early identification of malignant neoplasms in the oral cavity. Further study by the authors will evaluate fluorescence-guided photodynamic therapy for oral cancers in early stages.