Smoking and Lung Cancer: A Geo-Regional Perspective

Abstract

Lung cancer is the leading cause of cancer-related deaths worldwide. Non-small cell lung cancer (NSCLC) represents the most frequently diagnosed subtype of this morbid malignancy. NSCLC is causally linked to tobacco consumption with more than 500 million smokers worldwide at high risk for this fatal malignancy. We are currently lagging in our knowledge of the early molecular (e.g., genomic) effects of smoking in NSCLC pathogenesis that would constitute ideal markers for early detection. This limitation is further amplified when considering the variable etiologic factors in NSCLC pathogenesis among different regions around the globe. In this review, we present our current knowledge of genomic alterations arising during early stages of smoking-induced lung cancer initiation and progression, including discussing the premalignant airway field of injury induced by smoking. The review also underscores the wider spectra and higher age-adjusted rates of tobacco (e.g., water-pipe smoke) consumption, along with elevated environmental carcinogenic exposures and relatively poorer socioeconomic status, in low-middle income countries (LMICs), with Lebanon as an exemplar. This "cocktail" of carcinogenic exposures warrants the pressing need to understand the complex etiology of lung malignancies developing in LMICs such as Lebanon.

Keywords: early detection; global smoking patterns; lung cancer; pathogenesis; prevention; smoking.

Figure 1

Gender-specific smoking prevalence in the Middle East and North Africa (MENA) region and Lebanon. Upper panel: Projected smoking prevalence of any tobacco product for 2020 in the MENA region, expressed as percentage of smokers aged ≥15 years across each gender. Lebanon exhibits the highest smoking prevalence among females, and the fourth highest among males. Lower panel: Trend in smoking prevalence of any tobacco product in Lebanon, expressed as gender-specific percentage of smokers aged ≥15 years, accompanied by water-pipe prevalence (2009), as well as lung cancer incidence projected for 2020. Data schematically presented here were obtained from WHO Global Health Observatory Data Repository by country, (45) and (46).