All cancers involve the malfunction of genes that control
cell growth, division, and death. However, most of the
genetic abnormalities that affect cancer risk are not
hereditary, but instead result from damage to genes
(mutations) that occur throughout one's lifetime.
Damage to genes may be due to internal factors, such as
hormones or the metabolism of nutrients within cells, or
external factors, such as tobacco, chemicals, and
sunlight. (These non-hereditary mutations are called
"somatic mutations"). It is estimated that 5%-10% of all
cancers are strongly hereditary, meaning that individuals
who inherit a specific genetic alteration have a
very high risk of developing a particular cancer. It is
thought that many cancers result from a combination of
hereditary and environmental factors. (a.)
Lung cancer has been the most common
cancer in the world for several decades,
and by 2008, there were an estimated 1.61
million new cases, representing 12.7% of
all new cancers. It was also the most
common cause of death from cancer, with
1.38 million deaths (18.2% of the total).
The majority of the cases now occur in
developing countries (55%). Lung cancer is
still the most common cancer in men
worldwide (1.1 million cases, 16.5% of the
total), with high rates in Central-Eastern
and Southern Europe, North America
and Eastern Asia. Very low rates are still
estimated in Middle and Western Africa. According to the United States Environmental Protection Agency; smoking, radon, and secondhand smoke are the leading causes of lung cancer. Smoking causes an estimated 160,000 cancer deaths in the U.S. every year. And the rate among women is rising. On January 11, 1964, Dr. Luther L. Terry, then U.S. Surgeon General, issued the first warning on the link between smoking and lung cancer. Lung cancer now surpasses breast cancer as the number one cause of death among women in the United States. Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year in the U.S. About 2,900 of these deaths occur among people who have never smoked. (a.), (d.)
In females, lung cancer incidence rates
are generally lower, but, worldwide, lung
cancer is now the fourth most frequent
cancer of women (513 000 cases, 8.5% of
all cancers) and the second most common
cause of death from cancer (427 000
deaths, 12.8% of the total). The highest
incidence rate is observed in North
America (where lung cancer it is now the
second most frequent cancer in women),
and the lowest in Middle Africa (15th most
frequent cancer).
Because of its high fatality (the ratio of
mortality to incidence is 0.86) and the lack
of variability in survival in developed and
developing countries, the highest and
lowest mortality rates are estimated in the
same regions, both in men and women. (a.)
According to GLOBOCAN, an estimated 12.7 million new cancer
cases and 7.6 million cancer deaths occurred in 2008. Cancer is neither rare anywhere in the world, nor confined to high-resource countries. "Striking differences in the patterns of cancer from region to region are observed," Dr. Christopher Wild, IARC Director, stated: "Cervix and liver cancers are much more common in developing regions of the world, whereas prostate and colorectal cancers are more common in developed regions." (b.)
A higher proportion of the cancer burden occurs in less developed
regions of the world, both in terms of cancer incidence (56% of new cancer cases in 2008 occur within developing regions) and cancer mortality (63% of cancer deaths). The most commonly diagnosed cancers worldwide are lung (1.61 million, 12.7% of the total), breast (1.38 million, 10.9%) and colorectal cancers (1.23 million, 9.7%). The most common causes of cancer death are lung (1.38 million, 18.2% of the total), stomach (0.74 million, 9.7%) and liver cancers (0.69 million, 9.2%). (b.)
Top 5 facts sources:
The American Cancer Society. (2007). "Global Cancer Facts & Figures
2007" (pages 1-4). Retrieved December 9th, 2010.
GLOBOCAN. (2008). "Globocan 2008 Cancer Fact Sheet". Retrieved Dec, 2010.
International Agency for Research on Cancer. (2010). Press release: "IARC launches the definitive cancer statistics resource GLOBOCAN 2008". Retrieved Dec, 2010.
United States Environmental Protection Agency. "Health Risks" Retrieved Dec, 2010. Web page: http://www.epa.gov/radon/healthrisks.html