Bronchitis includes acute and chronic, and chronic bronchitis may cause small nodules within the lungs. Bronchitis can be categorized into acute tracheo-bronchitis and chronic bronchitis. Acute tracheo-bronchitis does not usually cause small nodules in the lungs, whereas chronic bronchitis is one of the high-risk factors for lung cancer, and the risk of lung cancer is significantly increased compared to those with non-chronic bronchitis. The reason for this has not been fully clarified, and some studies have suggested that it may be mediated through chronic inflammation. Lung cancer can be manifested as small nodules in the lungs in the early stage, so chronic bronchitis may lead to the emergence of small nodules in the lungs, but the development of cancer is the result of a combination of factors, and cannot be simply categorized to a single factor.