Laser‐induced fluorescence spectroscopy for in vivo diagnosis of non‐melanoma skin cancers

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Abstract
Background and Objectives Laser‐induced fluorescence spectroscopy is a non‐invasive technique previously used for detection of cancer in a variety of organ systems. The objective of this study was to determine whether in vivo laser‐induced fluorescence spectroscopy alone at the visible excitation wavelength of 410 nm could be used to detect non‐melanoma skin cancers. Study Design/Materials and Methods The system consisted of a nitrogen/dye laser tuned at 410 nm, an optical multichannel analyzer, and a fiber optic probe for excitation of tissue and collection of fluorescence emission. Two hundred and seventy nine measurements were performed from normal and abnormal tissues in 49 patients. Patients were classified as having either skin types I, II, or III. Biopsy of the abnormal tissues were then performed. Each measurement was assigned as either normal, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), pre‐cancerous, or benign. Total emission photon count was used as the discriminating index. A threshold value was calculated to separate normal tissue indices from indices of cancer tissues. The classification accuracy of each data point was determined using the threshold value. Results Cancers were classified 93, 89, and 78% correctly in patients with skin types I, II, and III, respectively. Normal tissues were classified 93, 88, and 50% correctly in patients with skin types I, II, and III, respectively. Using the same threshold, pre‐cancerous spectra were classified 78 and 100% correctly in skin types I and III, respectively. Benign lesions were classified 100, 46, and 27% correctly in patient with skin types I, II, and III, respectively. Conclusions In vivo laser induced fluorescence spectroscopy at 410 nm excitation and using the intensity of emission signal is effective for detection of BCC, SCC, and actinic keratosis, specially in patients with light colored skin. Lasers Surg. Med. 31:367–373, 2002.