RESUMO
Lung cancer (LC) is characterized as one of the most common and lethal types of cancers worldwide, with approximately 230.000 new cases each year in the US and 160.000 deaths are estimated for 2012. In Brazil, the outlook is also bleak, with 27,320 new cases expected in 2012, according to the Brazilian National Cancer Institute (INCA). LC is classified into two major histological types: small cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). In addition to sizable mortality and incidence, LC has low 5-year survival rates when compared to other types of common cancers such as breast and prostate, even with recent diagnostic and therapeutic advances. For the survival rate of patients with LC to increase, a greater understanding of the molecular events that lead to the emergence of this malignancy is necessary in order to identify genetic markers involved in tumor progression, and thus enable early detection and to develop new specific therapeutic strategies, allowing for a more individualized treatment in patients with LC. Different situations are classified as risk factors for the development of LC, but unquestionably, the most responsible risk factor for the high incidence of LC in the world population by far is smoking.