Cigarette smoking is the cause of 90 percent of the world's lung cancer cases.
Smokers who substantially reduce the number of cigarettes they smoke per day are exposed to lower amounts of a potent tobacco carcinogen, or cancer-causing agent. However, the reduction in the amount or concentration of the carcinogen exposure is often temporary and not proportional to the reduction in cigarettes smoked.
Researchers from the University of Minnesota Cancer Center measured the metabolites of a specific tobacco carcinogen, NNK, in the urine of smokers who were part of a smoking reduction program. The results would show whether smokers who reduce the number of cigarettes smoked per day also decrease their risk of lung cancer.
Investigators report an overall reduction in carcinogen levels at nearly all of the study intervals as the 92 patients who completed the study reduced the number of cigarettes smoked each day. Researchers say the results suggest people who are trying to cut back by smoking fewer cigarettes per day alter their smoking behavior by inhaling longer and deeper, which is known to alter a smoker's exposure to carcinogens. Investigators conclude, "The results indicate that some smokers may benefit from reduced smoking, but for most the effects are modest, probably due to compensation."
A team of epidemiologists reviewed the association between smoking and cancers not previously believed to be associated with tobacco use, such as cancers of the stomach, liver and kidney. They say: "Although 1 billion people worldwide already smoke and more will start, individuals who stop smoking reduce their smoking-related cancer risks effectively. A balanced public health strategy is therefore needed that not only prevents young individuals from starting to smoke, but also helps adults stop smoking."
Researchers from the National Cancer Institute discuss how the two studies highlight that tobacco's role as a cancer initiator and promoter is not only complex, but also remains one of the greatest global public health challenges. Given the strong evidence, NCI researchers say the most dramatic health benefits in the next half-century will happen when the number of smokers who quit significantly increases.