RESUMO
OBJECTIVE: To investigate a unique biomarker from the blood plasma and sputum of lung cancer patients based on native fluorescence analysis of body fluids. BACKGROUND: Conventionally, biomarkers indicative of malignancy are identified by biochemical or biophysical processes. Most of the cancer biomarkers, often useful in monitoring disease progression, have sensitivity and specificity in the range of 60%. METHODS: We employed synchronous fluorescence excitation spectroscopy (SFXS) and fluorescence emission spectroscopy for the native fluorescence analysis of blood plasma of 32 normal controls, 32 patients with lung cancer, and 32 patients with other types of cancer. RESULTS: Based on the native fluorescence analysis of blood plasma and sputum, we found that the structural protein elastin, with an excitation peak at 327 nm and an emission peak at 405 nm, is an exclusive biomarker for lung carcinoma with 77% sensitivity and 83% specificity from plasma alone, 92.3% sensitivity and 100% specificity from plasma acetone extract alone, and 66% sensitivity and 100% specificity from sputum alone. CONCLUSION: In this preliminary report with a limited number of lung cancer patients, we have used SFXS of plasma and sputa as the basis for a new technique identifying elastin as an exclusive lung cancer biomarker. This technique has the potential to become a new protocol for rapid and cost-effective screening and diagnosis of lung cancer.
