Disentangling tobacco-related lung cancer—genome-wide interaction study of smoking behavior and non-small cell lung cancer risk

Lung cancer poses a serious health problem worldwide being the first cancer in incidence and the leading cause of cancer death in developed countries (1). According to its histological characteristics lung cancer is subdivided into two types; the main one is non-small cell lung cancer (NSCLC) which originates from bronchial epithelial-cell precursors and small cell lung cancer (SCLC) that originates in neuroendocrine cells. NSCLC is the most abundant form of lung cancer comprising more than 80% of all lung cancers (2). It includes several subtypes such as adenocarcinomas, squamous cell carcinomas, and large cell carcinomas. Nowadays, squamous cell carcinoma incidence is decreasing while adenocarcinomas are increasing. Adenocarcinoma has become the predominant histological type worldwide, and this is more evident in women and never-smokers (3).