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Surgeon General report identifies more health hazards from smoking
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Colorectal and liver cancers, diabetes, rheumatoid arthritis, erectile dysfunction, age-related macular degeneration and other conditions have been added to the list of diseases caused by cigarette smoking or exposure to secondhand smoke, according to a new report issued by the Surgeon General of the United States.
The Health Consequences of Smoking — 50 Years of Progress: A Report of the Surgeon General, comes 50 years after the Surgeon General issued the first report on the health consequences of smoking, which concluded that smoking was a cause of lung cancer.
Major conclusions
The new report, issued by acting Surgeon General Boris D. Lushniak, MD, MPH, outlines updated findings on disease risks from smoking, and estimates that 5.6 million Americans currently aged younger than 18 years will die prematurely from smoking-related causes if current smoking trends are not curbed.
The report also concluded that cigarette smoking increases the risk for all-cause mortality in men and women, and that the relative risk for death from cigarette smoking has increased in the past 50 years.
“Smoking remains the leading preventable cause of premature disease and death in the United States,” Lushniak wrote in a preface to the report. “The science contained in this and prior Surgeon General’s reports provide all the information we need to save future generations from the burden of premature disease caused by tobacco use. However, evidence-based interventions that encourage quitting and prevent youth smoking continue to be underutilized.”
Effects on cancer risk
A number of meta-analyses have demonstrated that smoking confers an increased risk for liver cancer. According to the report, in one meta-analysis, current smoking carried an elevated risk for hepatocellular carcinoma in cohort studies (RR=1.7; 95% CI, 1.5-1.9) and case-control studies (RR=1.6; 95% CI, 1.2-2.1). In another meta-analysis, the association was stronger in cohort studies than in case-control studies.
The report also details sufficient evidence to conclude that there is a causal relationship between smoking and colorectal adenomatous polyps and colorectal cancer.
Current smokers have a higher risk for adenomas compared with never-smokers (RR=2.14; 95% CI, 1.86-2.46), and the association also was strong among former smokers (RR=1.47; 95% CI, 1.29-1.67). A number of meta-analyses concluded that current and/or former smoking increases the risk for colorectal cancer and related mortality, although the effect size in such analyses varied.
Although overall smoking rates have declined, the risk for developing adenocarcinoma of the lung has increased since the 1960s because of changes in the design and composition of cigarettes, according to the report.
There is a lack of sufficient evidence to establish a causal relationship between smoking and prostate cancer or breast cancer, but evidence suggests that smokers are more likely to die of prostate cancer than nonsmokers, and that active smoking and exposure to secondhand smoke increase risk for breast cancer, the report states.
In addition, patients with cancer who smoke have worse outcomes than cancer patients who do not smoke, researchers found.
Other findings
Evidence is now sufficient to conclude that the increase in risk for any kind of stroke from exposure to secondhand smoke is approximately 25% (HR=1.25; 95% CI, 1.12-1.38), according to the report.
Cardiovascular disease, not lung cancer, has been implicated as the largest smoking-attributable cause of death in the United States, and claims more lives of smokers aged 35 years and older annually than lung cancer. Moreover, exposure to secondhand smoke causes more deaths from cardiovascular disease than from lung cancer.
There also is evidence that suggests smoke-free laws and policies covering workplaces, restaurants and bars are associated with a reduction in coronary events (RR=0.85; 95% CI, 0.82-0.88), but the effect is not observed in people aged 65 years and older (RR=0.98; 95% CI, 0.953-1.008).
The report concluded that cigarette smoking is a cause of diabetes, and that the risk for developing diabetes is 30% to 40% higher for current smokers than for nonsmokers (RR=1.37; 95% CI, 1.31-1.44).
Research also has revealed a dose-response relationship: The risk for developing diabetes rises with an increase in the number of cigarettes smoked. Light smokers, defined in most studies as those who smoke fewer than 20 cigarettes per day, have a higher risk for developing diabetes compared with nonsmokers (RR=1.25; 95% CI, 1.14-1.37), but the effect is greater among heavy smokers compared with nonsmokers (RR=1.54; 95% CI, 1.4-1.68).
“Over the last 50 years, tobacco control efforts have saved 8 million lives, but the job is far from over,” Howard K. Koh, MD, MPH, assistant secretary for health at HHS, said in a press release. “This report provides the impetus to accelerate public health and clinical strategies to drop overall smoking rates to less than 10% in the next decade.”