Many countries in the Eastern Mediterranean region (EMR) are undergoing marked demographic and socioeconomic transitions. Cancer increasingly becomes a major contributing cause of morbidity and mortality. Primary prevention through lifestyle and environmental changes offers a large potential for reducing this burden. The aim of the study was to estimate the cancer burden attributable to major lifestyle and environmental risk factors.

We used age-, sex-, and cancer-specific incidence data from GLOBOCAN 2012. Risk factors being considered were smoking, alcohol, high body mass index (BMI), insufficient physical activity, diet (salt, red meat, processed meat, fruit, and vegetables consumption), suboptimal breastfeeding, infections, and air pollution. Prevalence of these risk factors came from different sources including international literature, World Health Organisation, NCD-RisC, or the Food and Agriculture Organization. Based on the prevalence of the selected risk factors and the relative risks obtained from meta-analyses, we estimated sex-specific population-attributable fractions (PAF) in the 22 countries of the Eastern Mediterranean region.

We estimated that about 43% (or 210,000 cases) of all new cancer cases in adults aged 30 years and older in 2012 were attributable to the selected eight potentially modifiable risk factors. In terms of risk factors, the highest PAF was estimated for infections (15.3%), followed by smoking 14.9% among men. In women, the highest PAF was estimated for insufficient physical activity (23.1%), followed by infections (12.2%). The EMR is culturally and economically heterogeneous region and the estimated PAF therefore varied greatly by country. The overall PAF ranged from 26.6% in Djibouti to 53.0% in Tunisia among men and from 38.3% in United Arab Emirates to 51.0% in Lebanon among women. In terms of risk factors, the highest PAFs for some risk factors were observed in Tunisia (36.0%) for smoking, in Egypt (5.8%) for high BMI, in Qatar (9.3%) for insufficient physical activity, in Afghanistan (24.8%) for diet, in Egypt (29.3%) for infections, and in Bahrain (3.4%) for PM_2.5 among men. Among women, the highest PAFs were estimated in Lebanon (5.2%) for smoking, in Kuwait (9.9%) for high BMI, in Kuwait (34.4%) for insufficient physical activity, in Afghanistan (12.1%) for diet, in Lebanon (4.1%) for suboptimal breastfeeding, in Somalia (27.6%) for infections, and in Bahrain (1.1%) for PM_2.5.

Reduction in exposure to major lifestyle and environmental risk factors may potentially prevent a substantial number of cancer cases. Although the contribution of the risk factors varied greatly between countries, strategies tackling smoking, programmes promoting healthy diet and physical activity, and policies controlling infections in the population would largely reduce the cancer burden in the EMR.