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).
TO BE CONTINUED..................................
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