International smoking-related burden of cancer and chronic obstructive pulmonary disease at the turn of the twenty-first century : Geographic and temporal variations within Europe and the United States

textabstractWhile smoking prevalence has declined or remained stable in most countries thanks to public awareness of the health hazard of smoking and the implementation of tobacco control policies, the burden of smoking-related diseases remains colossal and underestimated. Therefore, in this thesis, Joannie Lortet-Tieulent assesses the international burden of two smoking-related diseases —cancer and chronic obstructive pulmonary disease (COPD)— at the turn of the twenty-first century, with a special focus on Europe and the USA. This burden is examined through the gender (social norms on smoking), race (associated with socioeconomic status in the USA) and geographic location (impact of tobacco control policies and country income level) perspectives. First, the impact of gender on incidence trends of the four cancers that are the most associated with smoking are examined in Europe. Incidence trends reflect the delayed adoption of smoking by women compared with men, and the large declines in smoking prevalence in men. Second, cigarette design and content have evolved over time and the impact of these changes on the distribution of lung cancer types (histologies) on each sex is tracked. Having massively started to smoke when filtered/low tar cigarettes were made available, women mainly developed a different type of lung cancer (adenocarcinoma) compared with men (squamous cell carcinoma). However, as men switched to those so-called light cigarettes, more men developed adenocarcinomas. Third, in the USA, racial and ethnic disparities in the smoking-attributable burden of cancer are explored. Blacks have a higher burden of cancer than Whites, but the smoking-attributable fraction of cancer of Blacks is similar to that of Whites. The smoking-attributable fraction of the cancer burden of Asians and Hispanics is the smallest of all races/ethnicities. Geographical differences in the USA are also investigated, by comparing state-level smoking-attributable cancer deaths. At national-level, 29% of cancer deaths are attributable to cigarette smoking. The highest proportion of smoking-related cancer deaths are observed in the South of the USA (up to 34%), where tobacco is grown, tobacco control policies are weaker, cigarettes are more affordable, and large populations with low socioeconomic status (in whom smoking prevalence is the highest) live. Finally, international trends of COPD and lung cancer mortality rates are contrasted to better understand the role of smoking in COPD mortality. COPD mortality rates are decreasing globally, but for different reasons depending on the country income level. In high-income countries, COPD is probably declining due to the decrease in smoking prevalence and the improvement of COPD management. Meanwhile, progress in middle-income countries likely reflects declines in poverty (a risk factor for developing COPD), particularly among women, who seldom smoke cigarettes. In conclusion, while decreasing in some populations, the smoking-related burden of cancer and COPD is large and there is still a great potential to reduce it. Those health gains can be achieved by strengthening tobacco control. We have the ability to end the smoking epidemic during the twenty-first century.