lung cancer has a tremendous impact on US mortality, with an estimated 172,570 new cases and 163,510 deaths in 2005 in men and women combined. The epidemic of lung cancer in the 20th century is due primarily to increases in cigarette smoking, which is the dominant cause of lung cancer.

Lung cancer statistics
The following are a few of the latest lung cancer statistics:

• Lung cancer incidence and mortality rates increased markedly through most of the last century, first in men and then in women.
• Lung cancer now accounts for 13% of new cancer cases and 29% of all cancer deaths each year in the US.
• Death rates for lung cancer in women surpassed those for breast cancer in 1987, and lung cancer is now the leading cause of cancer deaths in both genders.
• In 2005, it is estimated that there will be 73,020 deaths among US women due to lung cancer, compared to 40,410 due to breast cancer.

The great variation in lung cancer mortality rates by state more or less parallels long-standing state-specific differences in tobacco use. For example, among men average annual age-adjusted lung cancer death rates for 1990 to 1996 were highest in Kentucky (103.4 per 100,000), where 33.1% of men were current smokers in 1997, and lowest in Utah (45.8 per 100,000), where only 16.1% of men smoked.

Among women, lung cancer death rates were highest in Nevada (45.8 per 100,000), where 29.8% of women were current smokers, and lowest in Utah (13.9 per 100,000), where only 11.5% of women smoked.

Preventing lung cancer
There are many ways to prevent lung cancer, including:

• Avoiding of tobacco use: Evidence suggests that the preventive effect of smoking cessation depends upon the duration and intensity of prior smoking and upon time since cessation. A 30% to 50% reduction in lung cancer mortality risk has been noted after 10 years of cessation.
• Avoiding known carcinogens: Studies have shown that prolonged exposure to known carcinogens such as asbestos increase the risk of becoming ill.

• Chemoprevention: Chemoprevention is the use of specific natural or synthetic chemical agents to reverse, suppress, or prevent carcinogenesis before the development of invasive malignancy. Studies have examined whether it is possible to prevent cancer development in the lung and other aerodigestive tract sites using chemopreventive agents.
  

Chemoprevention studies include efforts to control carcinogenic stages and risks in a population ranging from healthy individuals with no known risk factors to persons at high risk of developing cancer, such as patients cured of an initial cancer who are at elevated risk of developing another primary cancer.

Chemoprevention is not yet established in standard clinical practice, but there is intensive study of this strategy for cancer prevention in the lung and other epithelial sites. Such studies have served to develop both human models for the study of chemoprevention and specific chemopreventive regimens.

The field-cancerization hypothesis in upper aerodigestive tract malignancy, which predicts diffuse epithelial injury as the result of inhaled carcinogens, has guided the development of these studies. Clinical evidence for field carcinogenesis is found in the occurrence of premalignant lesions and multiple primary tumors.

Molecular studies provide further evidence for multistep and field carcinogenesis in the lung.

See also

• Causes and risk factors
• Detection and diagnosis
• Treatment options
• Prognosis
• Support