Tobacco use

Tobacco use, most commonly by smoking cigarettes, is a drug habit of many throughout the world. It is a significant risk factor for many malignancies, and respiratory and cardiovascular diseases and is a major cause of premature mortality throughout the world.

Epidemiology

The World Health Organization (WHO) estimates that ~7 million people die per year due to personal tobacco use, with a further 1.2 million dying from exposure to second-hand smoke ¹. Smoking was estimated in 2015 to be directly responsible for 11.5% of global mortality ¹⁰.

In 2015, a large systematic review found that ~25% of men and ~5% of women in the world smoked tobacco daily ¹⁰.

Smoking-related disease

Tobacco smoking markedly increases the risk of developing many diseases ^2-7. It is a major risk factor for malignancy with a good correlation with an individual's pack-year history ¹.

• malignancy: commonest histological type is adenocarcinoma

  • lung cancer: all histological forms

  • urothelial carcinoma: renal pelvis, ureter, bladder

  • head and neck malignancy

    • sinonasal carcinoma

    • pharyngeal

      • nasopharyngeal carcinoma

      • oropharyngeal carcinoma

      • hypopharyngeal carcinoma

  • esophageal carcinoma

  • hepatocellular carcinoma

  • pancreatic ductal adenocarcinoma

• respiratory disease

  • asthma

  • chronic obstructive pulmonary disease (COPD)

  • constrictive bronchiolitis

  • respiratory bronchiolitis (RB)

  • respiratory bronchiolitis-interstitial lung disease (RB-ILD)

  • desquamative interstitial pneumonia (DIP)

  • pulmonary Langerhans cell histiocytosis (PLCH)

  • idiopathic pulmonary fibrosis-usual interstitial pneumonia

  • combined pulmonary fibrosis and emphysema (CPFE)

  • acute eosinophilic pneumonia (AEP)

  • rheumatoid-arthritis-associated interstitial lung disease (RA-ILD)

  • diffuse alveolar hemorrhage (DAH) in Goodpasture syndrome

  • pulmonary alveolar proteinosis

  • COVID-19

• cardiovascular disease ⁵

  • atherosclerosis

  • hypertension

  • myocardial ischemia/infarction

  • heart failure

  • arrhythmias

    • atrial fibrillation

    • atrial flutter

    • paroxysmal tachycardia

  • cardiac arrest

  • aortic aneurysm

  • aortic dissection

  • thromboembolic venous disease

    • pulmonary embolism (PE)

    • deep vein thrombosis (DVT)

  • peripheral vascular disease

  • stroke

• musculoskeletal

  • fractures: smoking impairs bone healing ^11,12

  • osteoporosis

• autoimmune

  • ankylosing spondylitis

  • Crohn disease ⁷

  • rheumatoid arthritis

• ocular

  • cataracts

  • age-related macular degeneration

  • Graves orbitopathy

Diseases for which smoking decreases risk

• endometrial carcinoma ⁹

• ulcerative colitis ⁷

• Parkinson disease ⁸

• pre-eclampsia ¹³

Pathology

The chemical analysis of tobacco smoke has been intensively studied for more than a century, over which time more than 7,000 different substances have been found in the fumes. The International Agency for Research on Cancer (IARC), of the World Health Organization (WHO), has designated over fifty of these compounds as carcinogens. Toxic compounds found in the smoke include carbon monoxide, benzene, formaldehyde, polycyclic aromatic hydrocarbons, hydrogen cyanide, elemental lead and nitrosamines ¹.

However, it is nicotine, an alkaloid compound found in tobacco, which forms almost 95% of the chemical composition of the smoke, that is the primary driver for the addictive nature of tobacco usage ¹. Interestingly there is no conclusive evidence that nicotine itself is a carcinogen ¹⁴.

Methods of tobacco administration

Although the smoking of cigarettes is far and away the most prevalent form, tobacco is self-administered via a broad range of other methods including:

• smoking

  • predominantly cigarettes, including bidis, krekets, water pipes

  • pipes

  • cigars

• non-smoking forms

  • electronic cigarettes (a.k.a. e-cigarettes/vaping)

  • snuff

    • wet (snus)

    • dry

  • chewing loose leaf

Related pathology

• vaping-associated lung disease

• smoking-related lung diseases

  • smoking-related interstitial lung diseases