A new study in China has found that smokers are at increased risk of 56 different diseases. As you might expect, several types of cancer made the list; but, there were also diseases affecting numerous other body systems, from the brain to the liver and pancreas, and even the eyes.
Tobacco smoking continues to pose a major threat to public health worldwide, particularly in low- and middle-income countries. In China, smoking is associated with over a million deaths each year, and the number of smokers is increasing. The new study, a collaboration between the University of Oxford and several Chinese institutions, compared people who had never smoked, those who had smoked regularly at some point in their lives, and those who currently smoked, and looked at their risk of developing or dying from certain diseases over their lifetime.
This study was extensive, looking at 85 causes of death and 480 different individual diseases. The data came from the China Kadoorie Biobank. Over 512,000 adults were recruited to the study between 2004 and 2008, and they were followed up for a median of 11 years. Many more of the men who were studied had ever smoked regularly, at 74.3 percent compared with 3.2 percent of the women.
“About two-thirds of young Chinese men become cigarette smokers, and most start before they are 20. Unless they stop, about half of them will eventually be killed by their habit,” was the stark warning from Professor Liming Li, one of the senior authors, in a statement.
Compared with those who had never smoked, men who had smoked regularly at some time in their lives had about a 10 percent overall greater risk of developing any disease. The disease with the largest increased risk, at 216 percent, was larynx cancer. Men who regularly smoked and lived in urban areas were at the greatest risk of all – the authors noted that these men often start smoking younger and smoke more overall than those living in rural areas.
There was some good news, though – people who stopped smoking before any major health scares saw their risk of disease drop, after about 10 years, to the same level as for those who had never smoked at all.
The 56 diseases that were found to occur more in smokers of both sexes included cancers of the lungs, stomach, and bladder; diabetes; heart attack; aortic aneurysm; pneumonia; gastric ulcer; and cataracts. This was the first time that the long-term effects of smoking in the adult Chinese population have been so comprehensively studied.
Commenting on the results, lead author Dr Ka Hung Chan said, “The results are a stark reminder of the serious consequences of smoking and the benefits of stopping before any major illness develops. Although some associations were weaker than those seen in high-income populations, these are likely to be explained by the more recent widespread uptake of smoking in China.”
The study raises concerns about the future risks to health if smoking continues to become more common in China. Senior author Professor Zhengming Chen suggested how this risk could be curbed: “For China, a substantial increase in cigarette prices and effective package warning could save tens of millions of lives.”
The study is published in The Lancet Public Health.