RESUMO
BACKGROUND AND OBJECTIVES: Raman spectroscopy is a vibrational spectroscopic technique capable of providing details on the chemical composition, molecular structure and molecular interactions in cells and tissues. Its application of distinguishing normal and cancer tissue has been studied in a variety of sites, such as the cervix, lung, larynx and skin. The purpose was to explore spectral changes between normal and cancer tissue in the larynx using Raman spectroscopy to assess the feasibility of using Raman spectroscopy for the early diagnosis of laryngeal cancer. MATERIALS AND METHOD: Laryngeal tissue specimens (13 adjacent normal and 13 cancer tissues) were obtained from patients who underwent total laryngetomy or supracricoid laryngectomy with squamous cell carcinoma of the larynx. The specimens were stored -70 degrees C until use. These specimens were defrosted at room temperature. The Raman spectra from laryngeal tissue specimens could be obtained at 300 mW and 250 scan during 15 minutes of the signal acquisition time using FT-Raman spectroscopy (Bruker Co., Karsruhe, Germany). RESULTS: Raman spectra were different significantly between cancer and adjacent normal tissues of the larynx at 1446 cm-1, 1240 cm-1, 1335 cm-1, and 1655 cm-1 (p=0.007, 0.2, 0.2, 0.3, respectively). The difference of 1446 cm-1 means the change of CH2 bending mode in protein and lipid of malignant tissue. The change of 1335 cm-1 means a decrease in CH3CH2 to a wagging mode of collagen and polynucleotide chain of malignant tissue. The difference of 1240 and 1655 means a decrease in the alpha-helix conformation of collagen. CONCLUSION: This study demonstrates the differences of Raman units between laryngeal cancer and adjacent normal tissue using Raman spectroscopy. In future, Raman spectroscopy may become a useful tool of guided biopsy for accurate pathologic diagnosis and assessment of the adequacy of resection margins.