Abstract. Carcinogenesis of the respiratory system has been a widespread disease. In 2012 a total of 1.8 million lung cancer new cases were recorded, accounting for around 13% of all new cancer diagnoses. The most important risk factors for respiratory system cancers is tobacco smoking (active and passive). Occupational exposures to carcinogens (asbestos, diesel fumes, silica dust, radon, nickel, chromium, etc) are important causative factors. Also, ambient and indoor air pollution from particulate matter (PM10, PM2.5, <PM2.5) contribute substantially to initiation and promotion of lung cancer. Human lung tissues are exposed daily to air oxidants generated either endogenously or exogenously, but all aerobic organisms are protected against oxidative damage by evolutionary enzymatic and non-enzymatic antioxidant systems. Respiratory cancers and in particular lung cancer are initiated through the generation of reactive oxygen and nitrogen species (ROS/RNS), leading to oxidative stress and tissue inflammation. Both play a fundametal role in the initiation and progression of cellular and mitochondrial DNA damage, membrane lipid peroxidation and oxidative damage to proteins. Ambient PM has the ability to penetrate the respiratory system and particles are trapped deep inside the lung’s alveoli. The physicochemical characteristics of particles (size, transition metal content, speciation, stable free radicals) play an important role in oxidative stress. In turn oxidative stress from chronic exposure initiates the synthesis of mediators of pulmonary inflammation in lung epithelial cells and contributes to the initiation of carcinogenic mechanisms. Pulmonary cancer mechanisms have been linked to a series of biochemical pathways of DNA and lipid membrane oxidative damage, macrophage stimulation, telomere shortening, modulation of gene expression and activation of transcription factors with important role in carcinogenesis. This review presents scientific papers on the role of ROS and oxidative stress in the production of mediators of pulmonary inflammation and mechanisms of carcinogenesis from selected recent studies and reviews (most from high impact scientific publications) on the risks factors for developinmg cancer of the respiratory system.

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