page_title: Health effects of tobacco
section_title: Cancer
hierarchical_section_title: Health effects of tobacco / Health effects of smoking / Cancer
caption_attribution_description: English: Share of total cancer deaths attributed to tobacco smoking (which is inclusive of smoking and secondhand smoke). This impact is measured across total cancer types 2016.
context_page_description: Tobacco use has predominantly negative effects on human health and concern about health effects of tobacco has a long history. Research has focused primarily on cigarette tobacco smoking.
  Tobacco smoke contains more than 70 chemicals that cause cancer. Tobacco also contains nicotine, which is a highly addictive psychoactive drug. When tobacco is smoked, nicotine causes physical and psychological dependency. Cigarettes sold in underdeveloped countries tend to have higher tar content, and are less likely to be filtered, potentially increasing vulnerability to tobacco smoking related disease in these regions.
  Tobacco use is the single greatest cause of preventable death globally. As many as half of people who use tobacco die from complications of tobacco use. The World Health Organization estimates that each year tobacco causes about 6 million deaths with 600,000 of these occurring in non-smokers due to second hand smoke. In the 20th century tobacco is estimated to have caused 100 million deaths.
context_section_description: The primary risks of tobacco usage include many forms of cancer, particularly lung cancer, kidney cancer, cancer of the larynx and head and neck, bladder cancer, cancer of the esophagus, cancer of the pancreas and stomach cancer.  Studies have established a relationship between tobacco smoke, including secondhand smoke, and cervical cancer in women. There is some evidence suggesting a small increased risk of myeloid leukemia, squamous cell sinonasal cancer, liver cancer, colorectal cancer, cancers of the gallbladder, the adrenal gland, the small intestine, and various childhood cancers.  The possible connection between breast cancer and tobacco is still uncertain.
  Lung cancer risk is highly affected by smoking, with up to 90% of cases being caused by tobacco smoking. Risk of developing lung cancer increases with number of years smoking and number of cigarettes smoked per day. Smoking can be linked to all subtypes of lung cancer. Small Cell Lung Carcinoma (SCLC) is the most closely associated with almost 100% of cases occurring in smokers. This form of cancer has been identified with autocrine growth loops, proto-oncogene activation and inhibition of tumour suppressor genes. SCLC may originate from neuroendocrine cells located in the bronchus called Feyrter cells.
  The risk of dying from lung cancer before age 85 is 22.1% for a male smoker and 11.9% for a female smoker, in the absence of competing causes of death. The corresponding estimates for lifelong nonsmokers are a 1.1% probability of dying from lung cancer before age 85 for a man of European descent, and a 0.8% probability for a woman.
caption: Share of cancer deaths attributed to tobacco in 2016.[61]
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