In this study, using the latest GBD 2019 data, we addressed the burden of all cancers from 1990 to 2019 in the NAME countries. This study displayed a slight decrease in the DALYs/100,000 from all cancers among both sexes over the last three decades. In the NAME countries in 2019, ASMRs for smoking-attributed cancers among males and females were 40.4 and 4.1, respectively, with an increase among the female during the past three decades. The death rate per 100,000 people from 1990 to 2019 decreased by 12% in males and increased by 8% in females. Also, the declining trends in DALYs/100,000 rates were estimated at 16% and 3% during 30 years in males and females, respectively. Our results with regard to the increasing mortality trend of smoking-attributed cancers were in line with those of developed countries [17, 18].
In addition, an increasing DALYs trend is observed in some countries such as Lebanon, Egypt, Afghanistan, and Saudi Arabia. The highest ASMR and DALYs were observed in Lebanon, Turkey, and Palestine in 2019. The highest rates of ASMR and DALYs were related to the tracheal, bronchus, and lung cancer.
Previous studies have shown the high risk of smoking associated with the occurrence of cancers; a study in Iran reported that 53.5% of all lung cancer deaths were attributed to smoking . Furthermore, the number of smoking-attributed cancer deaths was estimated to be 342,854 among males and 40,313 among females in China in 2014, of which, respectively, 1.8% and 50% included second-hand smoking . A systematic review study in 2015 has shown that smoking is associated with pancreatic, mouth, esophagus, lung, and larynx cancers; the related mortality risk for cancers was reported to be 0.48 to 1.60 among current smokers and 0.70 to 1.68 among current cigar and/or pipe in the studies included in the systematic review . A comprehensive review using the GBD-2019 study from 1990 to 2016 reported smoking as an important risk factor for all cancers in India . The prevalence of smoking has been decreasing worldwide between 1990 and 2015 . However, the burden of smoking was among the top five risk factors in 109 countries and regions in 2015, an increase from 88 geographic regions in 1990. Therefore, the undeniable role of smoking in cancer mortality calls for the attention of health policymakers in the region .
The highest mortality rates in both sexes were observed in the age groups of 80 to 84 years and ≥ 85 years. However, ASMRs in males aged 60 < and females over 55 years have increased over the last three decades. DALYs in Lebanon in all age groups have increased significantly in 2019 compared to 1990.
In the present study, the highest rates of ASMR and DALYs were related to tracheal, bronchus, and lung cancer. As studies have shown, smoking is the single most significant and preventable risk factor of lung cancer [22, 23].
Additionally, our findings demonstrate that, compared to females of the other nations in the region, the DALYs rate of smoking-attributed cancers among Lebanese females in 1990 and 2019 at different ages were reported to be much higher, with Turkey ranking next. In Oman, Bahrain, and Algeria, DALYs rates in different age groups in 2019 have decreased compared to 1990. These results show that the DALYs rate of smoking-attributed cancers has a different pattern in NAME countries. Mons et al. (2018) estimated the burden of smoking-attributed cancers in 85,072 cases (58,760 male, 26,312 female) and found that it is responsible for 19% of all incident cancers. Also, the highest population-attributable fractions (PAFs) were seen in lung cancer, with 89% of male and 83% of female lung cancer cases were attributable to smoking . The standardized PAFs of cancers deaths attributable to smoking reported 22.2% and 4% of Chinese males and females, respectively . In the United States, 2.6 million DALYs were lost to smoking-attributed cancer (27% of all DALYs lost to cancer) in 2011. Additionally, smoking-attributed DALYs rates were higher in males than in females (968 vs. 557 per 100,000) . Other studies have also reported smoking-attributed cancer DALYs to be higher in males than in females [7, 20, 25]. Therefore, the DALYs rate of smoking-attributed cancers is significant and to reduce this burden, regional strategies are required. According to the present study, smoking-attributed cancer DALYs and ASMR have increased in females over the past three decades, indicating an increase in smoking among females. Large variations in the smoking-attributed cancer burden by sex and country reflect differences in the current and past prevalence of smoking. Smoking has been more prevalent in males than females in the past . Additionally, the smoking-attributed cancer burden has been reported to differ significantly between racial and ethnic groups in previous studies [24, 26, 27]. Considering the age-sex pattern, and different mortality trends in the countries of the NAME countries, it is necessary to provide appropriate age and sex groups tailored solutions for the countries.
The present study’s findings showed that smoking-associated lung, trachea, and bronchial cancers had the highest ASMR and DALYs rates in both sexes; stomach and pancreatic cancers were also ranked next. A study by Huang in 2022 showed that smoking is a significant risk factor for the development of kidney cancer in the female population . Findings from the study by Gram et al. show that compared to never-active and never-passive smokers, regular (former and current) smokers have a 21% higher overall risk of breast cancer . Nevertheless, in the general population, one out of every nine breast cancers case and in the smoking population, one out of every six can be prevented by not actively smoking . A large prospective cohort of about 19,000 population in 21 states of Columbia, and Puerto Rico has shown that smoking is an important prognostic factor for prostate cancer, and that the prostate cancer may be one of the leading causes of smoking-related deaths . According to a meta-analysis study in 2019, compared to never-smokers, current smokers and former smokers are respectively 56% (Hazard ratio: 1.5695% CI, 1.34–1.83) and 15% (Hazard ratio: 1.15; 95% CI, 1.06–1.26) more at risk for pancreatic cancer . A systematic review study has also shown that smoking is associated with all-cause mortality, and pancreatic cancers, especially of the mouth, esophagus, lungs, and larynx. .
According to the previous evidence, smoking and exposure to smoke are of the important causes of cancer DALYs and mortality . Fortunately, smoking is a very avoidable risk factor. So far, many efforts have been made nationally and globally to combat tobacco consumption . However, due to the diversity of tobacco products and the prevalence of consumption at a young age, there is still a long way to go to combat tobacco use. In addition, encouraging smoking cessation at an early age is an important way to reduce the mortality and DALYs rate as age differences in cancer incidence may be due to differences in smoking cessation rates between young, middle-aged, and elderly populations .
This study had some limitations. Under-reporting smoking due to social desirability bias (especially among females and the youths) may have led to underestimating the smoking-associated burden of cancers. Analyses and comparison of the smoking-attributed cancer DALYs and ASMR over 3 decades were of the present study’s strengths, which helps clarify the status of this risk factor in the NAME countries.