Susceptibility to Lung Disease and Cancer from Tobacco
Tobacco use, fat intake, alcohol consumption, and lack of exercise are the largest contributors to disease in the U.S. Approximately 34% of mortality in adults over age 25 is due to heart disease and 25% is due to cancer according to the Centers for Disease Control (1). Tobacco has been identified as the leading cause of lung disease. It is responsible for 80-90% of lung cancer cases (2). Correlations have been made between genetic traits among family members and susceptibility to disease from the use of tobacco.
There are various factors increasing a smokers susceptibility toward disease and cancer. The effects of smoking on the lung's ability to function properly opens the door to insult from carcinogens found in cigarette smoke. A study conducted in 1993 comparing the lung tissue of smokers and non-smokers found very distinct differences between the two groups. The lung tissue of smokers displayed obvious signs of damage and compromised ability to fight off disease causing agents; many of which are contained in the smoke of cigarettes. Contributing factors toward susceptibility which are highlighted from this study include impaired immune response mechanisms and cellular damage (3). The function of the immune system is to rid our bodies of foreign material or at least neutralize it. If the body cannot get rid of this material then it can interact with body tissues. Cigarettes and tobacco contain many cancer causing chemicals. Along with disabling the immune response and destroying the lung tissue chemicals can wreak cancerous havoc within the lung, esophagus, throat, and mouth. Chemicals found in tobacco smoke also destroy the cellular mechanisms which remove particles from the bronchial passages and results in 'smokers cough'.
Genetic factors are also likely to be involved in lung cancer susceptibility. The carcinogens found in tobacco are metabolized by enzymes called P450s and GSH, among others. These enzymes are produced in response to substances entering our body. Our genes carry the template for production of these enzymes. Genetic variation between families can result in enzyme variation, and therefore variation in the ability or rate of the break down of tobacco carcinogens in our body. Inability to effectively metabolize carcinogens puts us at higher risk for developing cancer. Since the metabolism of substances occurs as a result of the stepwise activity of a variety of enzymes, a combined effect may also raise the risk of lung cancer among tobacco users.
For a discussion about cancer development click here.
1. URL: http://www.cdc.gov/nccdphp/dash/ahsumm/ussumm.htm
2. Benhamou S., Bonaiti-Pellie C. 1995. Susceptability to Bronchial cancer: an example of genetic-environmental interaction. Annales de Biologie Clinique, 53(9):507-13.
3. Mancini NM., Bene MC., Gerard H., Chabot F., Faure G., Polu JM., Lesur O. 1993. Early effects of short-time cigarette smoking on the human lung: a study of bronchoalveolar lavage fluids. Lung, 171 (5) :277-91.
This page was prepared by Theresa L. Pedersen, UCD EXTOXNET FAQ Team. August 1997.