The global burden of cancer continues to increase largely because of the aging and growth of the world population alongside an increasing adoption of cancer-causing behaviors in economically developing countries. Based on the GLOBOCAN 2008 estimate, about 12.7 million cancer cases and 7.6 million cancer deaths are estimated to have occurred in 2008; of these, 56% of the cases and 64% of the deaths occurred in the economically developing world (Jemal et al., 2011; American Cancer Society, 2007).
One of the most prevalent cancer diseases in which 85-90% of the cases are exclusively caused by cigarette smoking is lung cancer (Suresh, 2011). Lung cancer is the uncontrolled growth of abnormal cells in one or both of the lungs. While normal cells reproduce and develop into healthy lung tissue, these abnormal cells reproduce faster and never grow into normal lung tissue. Lumps of cancer cells (tumors) then form and grow. Besides interfering with how the lung functions, cancer cells can spread from the tumor into the bloodstream or lymphatic system where they can spread to other organs (American Lung Association, 2010).
Lung cancer was the most commonly diagnosed cancer as well as the leading cause of cancer death in males in 2008 globally. Among females, it was the fourth most commonly diagnosed cancer and the second leading cause of cancer death. Lung cancer accounts for 13% (1.6 million) of the total cases and 18% (1.4 million) of the deaths in 2008 in the world (GLOBOCAN, 2008). This is because lung cancer is diagnosed at an advanced stage in a majority of patients, which is the primary reason behind the high mortality rate associated with this disease (Suresh, 2011).
The incidence of lung cancer has started to subside in the developed countries due to the decline in smoking rates but the incidence rises in the developing world because of the continuously high smoking rate in developing countries (Boffetta and Parkin, 1994).
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