deaths (ACS, 2007b). Lung cancer remains the leading cause of cancer deaths in both men and women; prostatic cancer is the most frequently diagnosed cancer in men, and breast cancer in women (ACS, 2007b).
Although several of the studies reviewed cancer at all sites, the committee chose to focus on selected sites, specifically leukemias, lymphomas, and lung, bone, renal, bladder, stomach, brain and other parts of the central nervous system, prostatic, and testicular cancer. Most of those may be found on the basis of the route of exposure (generally inhalation or ingestion) and the mechanism of clearance of radiologic and chemical toxicants. Testicular cancer, being the most common cancer among young men, is of special interest to Gulf War veterans, and some studies of veterans suggested a higher but nonsignificantly increased risk in them than in their nondeployed counterparts (IOM, 2006b). Prostatic cancer is the most frequently diagnosed cancer in men in the United States, and any slight increase in risk could result in large numbers of cases or deaths.
Lung cancer is the leading cause of cancer death in the United States and the second-most common cancer in both American men and women. An estimated 213,380 new cases of and 160,390 deaths from lung cancer were expected in 2007 in the United States, accounting for about 14.8% of all cancer diagnoses and 28.7% of all cancer deaths. Lung-cancer incidence in men has been declining substantially from a peak of 102 cases per 100,000 men in 1984; in women, the incidence is reaching a plateau after decades of increase (ACS, 2007b). In 2004 (the most recent year with available published incidence data), there were 60.0 new cases of lung cancer per 100,000 people in the United States (73.6 in men and 50.2 in women) and 53.3 deaths per 100,000 (70.3 in men and 40.9 in women) (Ries et al., 2007).
Lung cancer is classified into two main types based on the appearance of its cells. Non–small-cell lung cancer accounts for about 87% of all lung cancers and is divided into three subtypes based on size, shape, and chemical makeup: squamous-cell carcinoma (25-30% of all lung cancers) is linked to smoking and commonly found near a bronchus, adenocarcinoma (40% of all lung cancers) appears in the outer regions of the lungs, and large-cell undifferentiated carcinoma (10-15% of all lung cancers) is found in all areas and tends to metastasize quickly. The second main type, small-cell lung cancer, also known as oat-cell carcinoma, accounts for the remaining 10-15% and is almost always linked to smoking. Small-cell lung cancer originates primarily in the bronchi and tends to metastasize quickly throughout the body fairly early in the disease process. Tobacco-smoking is the predominant risk factor and is thought to account for about 87% of lung-cancer deaths. Other risk factors include exposures to such