What Are the Causes for Lung Cancer?

By: Dr. Nicola J. Nasser, MD, PhD                   

Smoking

 Cigarette smoke contains numerous carcinogens (1). Lung cancer incidence increases markedly in smoking people relative to non-smokers, and 85-90% of lung cancer patients are smokers (2, 3). The first reports that showed a correlation between smoking and lung cancer were published in the 1950s, with the most important report by Doll and Hill (4). In 1951, Doll initiated a prospective study about the effect of smoking on 34,439 physicians in the United Kingdom (5). The results of this research were published in 1954 and showed that lung cancer is 14 times higher among smokers compared to non-smokers (5). Heavy smokers suffered from lung cancer 25 folds more than non-smokers (5). A research that was published in Plos Medicine journal, showed that the

cumulative risk of dying from lung cancer before age 85 years was 22.1% for a male smoker and 11.9% for a female smoker, compared to nonsmokers were the probability of dying from lung cancer before age 85  was 1.1% for men, and 0.8% for women (6). Research investigations showed that all cigarette types have carcinogenic potential, including those with a filter (7). Passive smoking is correlated as well with lung cancer (8). Nargile, which is called also Shisha, Hookah, argila, or waterpipe smoking was also a subject of many scientific research investigating its effect on health (9, 10). The smoke of the Hookah includes many carcinogens such as polycyclic aromatic hydrocarbons which may induce lung cancer (9). The smoking of Hookah exposes the smoker to the risk of developing lung cancer, as with regular cigarette smoking  (9, 10).

Ionizing radiation

Radon²²² gas is the main source of ionizing radiation in residential areas. Radon is the second cause for lung cancer after cigarette smoking. Radon is a gas without a color or smell which is produced as part of the radioactive decay of uranium. Uranium is found in soil at different concentrations, and Radon is found at high concentrations in some mines. Several reports showed that there is higher incidence of lung cancer among mining workers, which was attributed to Radon. There  are variable concentrations of radon in different residential areas, and its concentration in rooms and houses depends on the rate of its production versus level of ventilation. Higher production of radon may depend on the land on which the house is built, and probably on the levels of residual uranium in the soil used in the building concrete. Ventilation can assist in decreasing radon levels in houses. Not surprisingly, high levels of radon may be found in basements, and closed store rooms were ventilation is not adequate.  Research reports show that there is a correlation between radon gas levels in residential buildings and the incidence of lung cancer there (11, 12). Cigarette smokers who get exposed to radon gas, suffers detrimental risk which is synergistic, rather than merely additive. According to estimates, exposure to radon gas accounts for 10% of lung cancer cases (13). In the United States, Canada, and Europe there are several tests to residential buildings in order to determine radon levels and the radiation doses it emit. For more information about the detection of radon in residential houses, and what to do if radon levels are high, we found the following guides very useful: Radon- a guide for Canadian homeowners (14), and Home Buyer's and Seller's Guide to Radon (15).

 Asbestos exposure

Asbestos was in wide use in the last century, especially before its harms on health were identified.  It was used for construction of houses roofs, water containers, pipes, etc. Asbestos is found naturally is asbestos rocks, and was used for paving roads. Exposure to asbestos fibers, in the form of asbestos dust results in inhalation of asbestos to the lungs. Asbestos in the lungs causes chronic inflammation, especially in the lung pleura, which may end in cancer of the pleura, called mesothelioma (16).

Air pollution

Air pollution is another cause for lung cancer. A research published in the New England Journal of Medicine found an association between air pollution and mortality in six US cities (17). 

References:

1)      Tobacco carcinogens, their biomarkers and tobacco-induced cancer. Stephen S. Hecht. Nature Reviews Cancer 3, 733-744 (2003). To read this article press here لقرأة هذا المقال اضغط هنا .

2)      Lung cancer in never smokers: a review. Janakiraman Subramanian, Ramaswamy Govindan. Journal of Clinical Oncology, Vol 25, No 5: pp. 561-570 (2007). To read this article press here لقرأة هذا المقال اضغط هنا .

3)      Epidemiology of Lung Cancer. Anthony J. Alberg, Jean G. Ford, Jonathan M. Samet. Chest, vol. 132 no. 3 suppl 29S-55S (2007) To read this article press here لقرأة هذا المقال اضغط هنا

4)      Smoking and carcinoma of the lung: preliminary report. Doll R, Hill AB. Br Med J. 2: 739-748 (1950). To read this article press here لقرأة هذا المقال اضغط هنا

5)      Doll R, Peto R, Boreham J, SutherlandI. Mortality in relation to smoking: 50 years' observation on male British doctors. BMJ 328: 1519 (2004). To read this article press here لقرأة هذا المقال اضغط هنا

6)      Lung Cancer Occurrence in Never-Smokers: An Analysis of 13 Cohorts and 22 Cancer Registry Studies. Thun MJ, Hannan LM, Adams-Campbell LL, Boffetta P, Buring JE, et al. PLoS Med 5(9): e185.doi:10.1371/journal.pmed.0050185 (2008) To read this article press hereلقرأة هذا المقال اضغط هنا

7)      Cigarette filter ventilation is a defective design because of misleading taste, bigger puffs, and blocked vents. Kozlowski LT, O'Connor RJ. Tob Control, 11 suppl 1:140-150 (2002). To read this article press here لقرأة هذا المقال اضغط هنا

8)      Active and passive smoking in relation to lung cancer incidence in the Women's Health Initiative Observational Study prospective cohort. Wang A, Kubo J, Luo J, Desai M, Hedlin H, Henderson M, Chlebowski R, Tindle H, Chen C, Gomez S, Manson JE, Schwartz AG, Wactawski-Wende J, Cote M, Patel MI, Stefanick ML, Wakelee HA.Ann Oncol. 26:221-30 (2015).  To read this article press here لقرأة هذا المقال اضغط هنا

9)      Polycyclic aromatic hydrocarbons, carbon monoxide, "tar", and nicotine in the mainstream smoke aerosol of the narghile water pipe. Shihadeh A, Saleh R. Food Chem Toxicol; 43: 655-661 (2005). To read this article press here لقرأة هذا المقال اضغط هنا

10)  The water pipe: time for action. Maziak W. Addiction; 103: 1763-1767 (2008). To read this article press here لقرأة هذا المقال اضغط هنا

11)  Residential Radon Exposure and Lung Cancer in Sweden. Goran Pershagen et al. N Engl J Med 1994; 330:159-164 (1994). To read this article press here لقرأة هذا المقال اضغط هنا

12)  Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies. Darby s. et al. BMJ 330:223 (2005). To read this article press here لقرأة هذا المقال اضغط هنا

13)  Radon exposure: Can we make a difference? Ray Copes, Jeff Scott. CMAJ, 177,10 (2007). To read this article press here لقرأة هذا المقال اضغط هنا 

14)  Radon: a guide for Canadian homeowners. Ottawa: Canadian Mortgage and Housing Corporation and Health Canada; 1997, 2007. Available: http://www.housing.yk.ca/pdf/radon_guide.pdf (accessed September 25, 2015).

15)   Home Buyer's and Seller's Guide to Radon. United States Environmental Protection Agency. Available: http://www.epa.gov/radon/pubs/hmbyguid.html#1.b.  (accessed September 25, 2015).

16)  Asbestos Is Still With Us: Repeat Call for a Universal Ban,  Ramazzini, Collegium. Archives of Environmental & Occupational Health, 65:3, 121 - 126  (2010).  To read this article press here لقرأة هذا المقال اضغط هنا

17)  An association between air pollution and mortality in six US cities. Douglas W. Dockery, C. Arden Pope, Xiping Xu, John D. Spengler, James H. Ware, Martha E. Fay, Benjamin G. Ferris, Jr., and Frank E. Speizer. N Engl J Med; 329:1753-1759 (1993). To read this article press here لقرأة هذا المقال اضغط هنا