Abstract

Cancer is the second cause of death worldwide. According to the WHO, 14 million new cancers and 8.2 million of cancer-related deaths occurred in 2012, and it is expected that the number of new cases will rise by about 70% over the next 20 years. Lung cancer alone was responsible for approximately 1,590,000 deaths in 2012, being the leading cause of cancer death worldwide. Overall, it is estimated that exposure to tobacco accounts for about 21% of cancer mortality worldwide. A stron causative relationship between tobacco consumption and several types of cancers have been established, including oral, oropharyngeal, digestive and bladder, among others, but the most relevant association occurs between lung cancer and smoking. Regarding lung cancer, the principal carcinogens in cigarette smoke are the tobacco specific nitrosamines and polycylic aromatic hydrocarbons, which alter the smoker's DNA, causing mutations that stimulate cancer development. Carcinogenesis begins years before symptoms or clinical diagnosis, when a malignant cell losses its protective cell-cycle control mechanisms and begins uncontrolled replication. The clinical presentation and the different diagnostic methods varies depending on the distinctive histological type of lung cancer. In this chapter we will review the epidemiology of the most frequent tobacco-related cancers, some clinical aspects, and how carcinogens from tobacco lead to the development of cancer.