In 2011 the total number of expected cancer cases in the USA is 1,596,670 with 571,950 estimated deaths from cancer. The expected number of new lung cancer cases is 221,130 (115,060 men and 106,070 women), of which a total of 156,940 are expected to die from the disease (85,600 men and 71,340 women) (1). These data place lung cancer as the second most commonly diagnosed malignancy, and as the leading cause of cancer-related deaths in both men and women in the USA (1).
Amongst the known risk factors for developing lung cancer, cigarette smoking occupies the first place in importance (more than 90% of cases), followed by occupational and environmental exposure to adon, asbestos, second-hand smoke, chromium, arsenic, cadmium, organic chemicals, air pollution, radiation, and a previous history of tuberculosis. In those that develop lung cancer at a younger age, genetic susceptibility is also considered an important contributing risk factor (1).
The tumor cell type and the stage at presentation affect the prognosis and survival after treating lung cancer patients. Accurate diagnosis with confirmed cell type is of utmost importance. Lung cancers are divided into two main histologic types: non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). The histologic classification of lung cancer has undergone several revisions since the original 1967 recommendation proposed by the World Health Organization (WHO). The most significant update took place in 1999, followed by a slight change in 2004 (2–5). The revised cellular classification for NSCLC and SCLC summarizing the 1999 and 2004 WHO recommendations is presented in Table 7.1.