The American Cancer Society, NCI and the Centers for Disease Control and Prevention reported that the incidence of cancer in both men and women has shown a decrease of 0.8% annually from 1999 to 2005. The incidence of three major cancers (lung, prostate, colorectum) affecting men, showed a decrease of 1.8% each year from 2001 to 2005. On the other hand, the rate of breast and colorectum cancer in women showed a decrease of approximately 0.6% each year from 1998 to 2005. However, the rate of lung cancer in women remained steady from 1998 to 2005. The decrease in the incidence of cancer over the last two decades has inevitably translated into a decrease in the number of individuals who die of cancer each year. This decline in both incidence and mortality associated with all cancers has been observed in all ethnic and racial groups. However, American Indians and Alaskan Natives exhibit different incidences and mortality rates. However, the incidence of certain cancers such as pancreatic cancer in women, esophageal cancer in men and hepatocellular cancer in both the sexes has shown an increase over the past few years. The incidence of cancer and the associated mortality rates have shown a reduction over the last two decades mainly due to the administration of diverse range of prevention, early detection and effective treatment strategies (Schottenfeld et al 2006). Epidemiology of Lung Cancer in U.S: Literature Review Lung cancer in both sexes is the major cause of death in the United States of America. According to 2007 database of The US National Cancer Institute’s Surveillance Epidemiology and End Results 371,000 new cases of lung cancer were diagnosed in the United States. Out of the total of 371,000 lung cancer cases, 173,000 were men while 198,000 were women. According to an estimate by The American Cancer Society, 219,440 new cases of cancer were diagnosed while 159,390 individuals died of cancer in 2009 in the United States of America. This accounted for around 15% of all new cases of cancer diagnosed and 28% of all deaths associated with cancer in the year 2009. A recent statistics revealed that the number of Americans who die of lung cancer is greater than the number of deaths from colorectum, breast and prostate cancer combined. Previously lung cancer was very rare however, its prevalence increased rapidly in the 20th century due to the widespread use of tobacco products (Conference/Workshop on Lung Cancer Epidemiology and Industrial Applications of Sputum Cytology 2007). The correlation between lung cancer and cigarette smoking has not only been determined epidemiologically but the relation has also been confirmed due to the identification of carcinogens in cigarette smoke. Cigarette smoking is responsible for causing more than 90% of lung cancer cases. The smoking patterns in both the sexes have shown a change over the last two decades thus, since the 1990s, the incidence and mortality of lung cancer in men have decreased. However, in women both the incidence of lung cancer and the mortality rate has increased over the last two decades due to the increase in the number of women using tobacco products. Apart from the consumption of tobacco products, other environmental risk factors include the exposure of environmental cigarette smoke and poisoning with certain heavy metals such arsenic, chromium, iron oxide and nickel.