Lung Cancer is Most Closely Related to Smoking
Lung cancer is the cancer most strongly associated with smoking, with smoking responsible for more than 80% of all lung cancer cases and causing all four major histologic types (adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and small cell carcinoma). 1
Primary Smoking-Related Cancer
- Lung cancer represents the leading smoking-attributable malignancy, accounting for 90% of male lung cancers and 79% of female lung cancers caused by tobacco use 2
- Smoking is the single most important cause of lung cancer, responsible for over 80% of cases globally 1
- The risk of developing lung cancer is 20-40 times higher in lifelong smokers compared to non-smokers 2
- All four major histologic types of lung cancer (adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and small cell carcinoma) are caused by cigarette smoking 1
Additional Smoking-Related Cancers
While lung cancer is the primary smoking-related malignancy, smoking also causes cancers throughout the aerodigestive tract:
- Oral cavity and pharyngeal cancers show a causal relationship with smoking, with up to 75% of oral cancer cases in the United States attributable to tobacco and alcohol use 1, 3
- The American College of Oncology confirms smoking causes oral cavity cancer with convincing evidence of large increased risk (relative risk ≥2.0) 3
- Other smoking-related cancers include esophageal, laryngeal, bladder, pancreatic, gastric, kidney, ovarian, colorectal, and cervical cancers 1
Dose-Response Relationship
- The lung cancer risk increases directly with pack-years of smoking history (number of cigarette packs per day multiplied by years of smoking) 1
- Risk increases with the number of cigarettes smoked per day and the number of years spent smoking 1
- Environmental tobacco smoke (secondhand smoke) also increases lung cancer risk, with exposed nonsmokers having a 24% increased risk (RR 1.24) 1
Impact of Smoking Cessation
- After smoking cessation, lung cancer risk decreases by 30-50% after 10 years of abstinence compared to current smokers 1
- However, former smokers maintain permanently elevated lung cancer risk compared to never-smokers, even after 40 years of abstinence 1
- The benefits of cessation depend on smoking duration; shorter smoking duration before quitting results in greater risk reduction 1