This blog post was written by Enrique Diaz-Guzman, MD, Assistant Professor of Medicine, Associate Program Director, Pulmonary & Critical Care Fellowship, University of Kentucky
COPD and Lung Cancer are among the most important health care problems in the world. According to the World Health Organization, COPD will become the fourth leading cause of worldwide mortality by the year 2020. Lung cancer is currently the second most common type of cancer in adults, and is the leading cause of deaths due to cancer in the world.
The main risk factor for developing both lung cancer and COPD is cigarette smoking. Cigarette smoke contains more than sixty substances known to cause cancer (carcinogens). People with a long-term history of tobacco use have a 10 to 30 fold increase in the risk of lung cancer compared to never smokers.
Although cigarette smoking is the main risk factor for the development of lung cancer in people with COPD, the risk exists even in the absence of tobacco use and appears to be inversely related to lung function. In other words, the worse the lung function is, the higher the chance of developing lung cancer. For example, research studies suggest that people with severe COPD have two to six times more chances of developing lung cancer compared to people with normal lung function. Moreover, even in patients with mild COPD, lung cancer represents a major health problem, as it represents one of the most common causes of death (up to a third of all deaths in mild COPD are related to lung cancer problems).
There are many factors that possibly explain the link between COPD and development of lung cancer. Although it is clear that cigarette smoke is a “carcinogen”—a substance that directly induces the formation of cancer cells—other factors participate in the development of cancer. Patients with COPD without history of smoking tobacco also have a double increased risk for lung cancer. Research studies have found that patients with COPD have increased indices of inflammation and oxidative stress in the lungs. This inflammatory process may accelerate cell growth and participate in defective mechanisms of repair that facilitate the development of cancer cells.
Smoking cessation is key to the prevention of lung cancer; nevertheless, people with COPD who used to smoke will continue to have an increased risk for lung cancer compared to those who never smoke. Although some researchers have tried to use anti-inflammatory medications to reduce the risk of lung cancer in people with COPD, currently there is no evidence that any of the inhaled corticosteroids reduces the risk of lung cancer.
The treatment of lung cancer in patients with COPD is not different than in people without COPD, with the exception of an emphasis in the control of mucus production and the use of inhaled bronchodilators. The treatment of lung cancer depends on the stage of the disease, and frequently involves a multimodality approach, including surgery, chemotherapy and radiation therapy.