Laser-induced fluorescence spectroscopy for skin cancer diagnostics

Objective: The goal of this pilot study was to determine whether in vivo laser-induced fluorescence intensity may be used to distinguish normal skin from malignant lesions. Materials and Methods: The system consisted of a nitrogen/dye laser tuned at 410 nm an optical multichannel analyzer, and a fiber optic probe designed for excitation of tissue and collection of fluorescence emission. The intensity of fluorescence at the wavelength of 500 nm (I-500) was used as the discriminating index. All data were normalized with respect to fluorescence of a standard dye. A total of 117 measurements were performed from normal and abnormal tissues in 28 patients. Patients were classified as having either of skin types I, II or III. Following the measurement, a biopsy of the abnormal tissue was performers. Using the biopsy results, each measurement was assigned under one of the following categories: basal cell carcinoma, squamous cell carcinoma, precancerous lesions, and benign lesions. Results: In patients with skin type I, the I-500 index for basal cell carcinoma, squamous cell carcinoma and precancerous lesions were significantly different than that of normal tissue. There was no significant difference between I-500 of benign lesions and normal tissue. In patients with skin type II, the I500 for basal cell carcinoma and squamous cell carcinoma was significantly different than that of normal tissues. Benign tissue could not be distinguished from normal tissue. In patients with skin type III, basal cell carcinoma and precancerous lesion could be easily distinguished from normal tissues. However, there was a statistically significant difference between benign and normal tissue. Conclusion: This pilot study indicated that the laser-induced fluorescence intensity of skin may be used to distinguish normal from cancerous and precancerous tissue.