What is the leading cause of cancer?

Leading Cause of Cancer

Cigarette smoking is the leading cause of cancer worldwide, responsible for approximately 80% of all lung cancer cases and 30% of all cancer deaths. 1

Epidemiology of Cancer and Tobacco's Role

• Lung cancer is the leading cause of cancer-related deaths globally, with 1.6 million new diagnoses and 1.4 million deaths annually (18% of all cancer deaths) 1
• Tobacco use is the single most significant preventable cause of cancer, with more than 440,000 Americans dying from smoking-related diseases each year 1
• The relationship between smoking and cancer follows a dose-response pattern, with increased risk associated with number of cigarettes smoked, deepness of inhalation, and duration of smoking 1
• Smoking is causally linked with high relative risk (RR ≥2.0) for lung, oral, pharyngeal, laryngeal, esophageal, bladder, kidney, and pancreatic cancers 1

Mechanisms and Risk Factors

• Besides active cigarette smoking, other tobacco-related risk factors include exposure to secondhand smoke, pipe and cigar smoking 1
• Additional environmental risk factors for lung cancer include occupational exposure to carcinogens (asbestos, nickel, chromium, arsenic), radiation (including radon gas), and indoor/outdoor air pollution 1
• Non-smoking-related lung cancer is becoming recognized as a distinct disease entity, particularly in Asian countries, with specific molecular and genetic tumor characteristics 1
• Women are overrepresented among younger lung cancer patients, suggesting potential gender-specific differences in susceptibility to lung carcinogens 1

Impact on Different Cancer Types

• Smoking has convincing evidence of moderate risk (RR 1.35-1.99) for leukemia, colon, stomach, and cervical cancers 1
• Probable links exist between smoking and prostate and liver cancers 1
• Lung cancer risk is not reduced by switching to filters or low-tar/low-nicotine cigarettes 2
• In cancer patients, continued tobacco use after diagnosis is associated with poor outcomes including increased treatment-related toxicity, increased risk of second primary cancer, decreased quality of life, and decreased survival 2

Prevention Strategies

• Smoking cessation can dramatically reduce lung cancer risk, especially if discontinued early in life 2
• Consumption of at least five servings of vegetables and fruits daily may reduce the risk of lung cancer among both smokers and nonsmokers 1
• Lung cancer screening is recommended only for a specific high-risk population: individuals aged 55-74 years with ≥30 pack-year smoking history who currently smoke or quit within the past 15 years 3
• Comprehensive tobacco control efforts, including preventing initiation and treating dependence, are essential to address the lung cancer epidemic 4

Global Perspective

• The incidence of lung cancer in different countries parallels changes in cigarette consumption 2
• Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these regions 1
• The economic cost of caring for lung cancer patients in the United States exceeds $12 billion annually, with additional billions lost in productivity 1
• Education and socioeconomic status affect both cancer incidence and outcomes, with a disproportionate burden among the poor and less educated 1