Smoking and cancer risk

How does smoking tobacco cause cancer?

Tobacco smoking is the leading cause of cancer worldwide, causing almost 6 million deaths each year. These deaths could be prevented if people did not smoke.

Tobacco smoke contains many known carcinogens – substances that cause cancer. Many people know that smoking causes lung cancer, but it can also cause many other types, including breast, bowel (also known as colorectal), blood, bladder, liver, mouth, pancreatic and stomach cancer.

Passive smoking (being exposed to someone else’s tobacco smoke) also increases the risk of lung cancer, and is particularly dangerous for children.  

All forms of tobacco cause cancer regardless of whether they are smoked (such as pipes, cigars, 'light' cigarettes, roll-ups and shishas) chewed, sucked or inhaled (such as smokeless tobacco and betel quid).

E-cigarettes ('vaping') do not contain tobacco, but there is conflicting information about their safety. They are not regulated and their long-term impact on health is not yet known.

Not smoking or giving up smoking is the best way to reduce your own cancer risk and the risk to those around you, followed by maintaining a healthy weight through eating a healthy diet and keeping active. There is lots of free advice and support available to help with giving up smoking, including from the NHS


The International Agency for Research on Cancer provides information on tobacco and second-hand smoke. The National Institute of Health explores how tobacco causes cancer. Centers for Disease Control and Prevention has information on how smoking harms your health and E-cigarettes. The European Code Against Cancer has much more information about smoking and cancer.