Incidence and Mortality
Cigarette Smoking is the Primary Risk Factor
The Biology of Carcinogenesis

Incidence and Mortality

Lung cancer has a tremendous impact on U.S. mortality, with an estimated 215,020 new cases and 161,840 deaths in 2008 in men and women combined.[1] Lung cancer incidence and mortality rates increased markedly throughout most of the last century, first in men and then in women. The trends in lung cancer incidence and mortality rates have closely mirrored historical patterns of smoking prevalence, after accounting for an appropriate latency period. Because of historical differences in smoking prevalence between men and women, lung cancer rates in men have been consistently declining since 1990, whereas consistent declines in women have not yet been seen.[2] Lung cancer now accounts for 15% of new cancer cases and 29% of all cancer deaths each year in the United States. Lung cancer is the leading cause of cancer deaths in both men and women. In 2008, it is estimated that 71,030 deaths will occur among U.S. women due to lung cancer, compared with 40,930 deaths due to breast cancer.[1]

The epidemic of lung cancer in the 20th century was primarily due to increases in cigarette smoking, the predominant cause of lung cancer. The threefold variation in lung cancer mortality rates across the United States more or less parallels long-standing state-specific differences in the prevalence of cigarette smoking. For example, average annual age-adjusted lung cancer death rates for 1996 to 2000 were highest in Kentucky (78 per 100,000) where 31% were current smokers in 2001; whereas the lung cancer death rates were lowest in Utah (26 per 100,000), which had the lowest prevalence of cigarette smoking (13%).[3]

Surgical treatment or radiation therapy is the treatment of choice for early stages of cancer. Unfortunately, initial success with these modalities is overshadowed by the potential for long-term development of second primary tumors.[4] Therefore, new approaches for controlling lung cancer are being developed, including prevention strategies, such as cancer chemoprevention.

Understanding the biology of carcinogenesis is crucial to the development of effective chemoprevention. Two basic concepts supporting the chemoprevention approach are the multistep nature of carcinogenesis and the diffuse field-wide carcinogenic process. Epithelial cancers in the lung appear to develop in a predictable series of steps extending over years. Epithelial carcinogenesis is conceptually divided into three phases: initiation, promotion, and progression. This process has been inferred from human studies identifying clinical-histological premalignant lesions (e.g., metaplasia and dysplasia). The concept of field carcinogenesis is that multiple independent neoplastic lesions occurring within the lung can result from repeated exposure to carcinogens, primarily tobacco. Patients developing cancers of the aerodigestive tract secondary to cigarette smoke also are likely to have multiple premalignant lesions of independent origin within the carcinogen-exposed field. The concepts of multistep and field carcinogenesis provide a model for prevention studies.[5]

References

1. American Cancer Society.: Cancer Facts and Figures 2008. Atlanta, Ga: American Cancer Society, 2008. Also available online. Last accessed October 1, 2008. 
   
   
2. Edwards BK, Brown ML, Wingo PA, et al.: Annual report to the nation on the status of cancer, 1975-2002, featuring population-based trends in cancer treatment. J Natl Cancer Inst 97 (19): 1407-27, 2005.  [PUBMED Abstract]
   
   
3. Weir HK, Thun MJ, Hankey BF, et al.: Annual report to the nation on the status of cancer, 1975-2000, featuring the uses of surveillance data for cancer prevention and control. J Natl Cancer Inst 95 (17): 1276-99, 2003.  [PUBMED Abstract]
   
   
4. Lippman SM, Hong WK: Not yet standard: retinoids versus second primary tumors. J Clin Oncol 11 (7): 1204-7, 1993.  [PUBMED Abstract]
   
   
5. Lippman SM, Benner SE, Hong WK: Cancer chemoprevention. J Clin Oncol 12 (4): 851-73, 1994.  [PUBMED Abstract]
   
   

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