Tobacco-related deaths have been declining steadily in most developed countries; however, China now produces and consumes about 40 percent of the world's cigarettes, with much of the rapid increase taking place since the early 1980s, involving almost exclusively only men.
Approximately 18,000 incident cancers were recorded during 7 years of follow-up of the ~500K cohort. Cox regression yielded adjusted risk ratios (RRs) comparing smokers (including those who had stopped because of illness but not those who had stopped by choice) with never-smokers.
Among the major findings:
- Sixty-eight percent of men in the study were smokers, and they had a 44 percent increased risk of developing cancer compared with never smokers.
- This excess risk accounted for 23 percent of all cancers that arose between the ages of 40 and 79 years, with significantly elevated risks of cancers of the lung, liver, stomach, oesophagus, and a collection of five other minor sites.
- Among ex-smokers (~7%) who had stopped by choice, there was little excess cancer risk within 15 years after quitting.
- In contrast to men, only three percent of females in the study were smokers, and they experienced a 42 percent increased risk of cancer compared with never smokers.
- Smoking causes an estimated 435,000 new cancers (360,000 in men and 75,000 in women) each year in China.
High male uptake rates before the age of 20 years and nearly universal use of cigarettes foreshadow substantial tobacco-attributed risks in China. Widespread smoking cessation offers China one of the most effective, and cost-effective, strategies for avoiding cancer and premature death over the next few decades.