World No Tobacco Day: The Single Biggest Preventable Cause of Cancer

What this observance is

Every May 31, World No Tobacco Day draws global attention to the harms of tobacco use. The World Health Organization created the observance in 1987 to inform people about the dangers of tobacco, the practices of the tobacco industry, and what individuals and communities can do to protect their health. Of all cancer awareness efforts, this is one of the most directly actionable: tobacco is the leading preventable cause of cancer.

Why tobacco and cancer are so closely linked

According to the National Cancer Institute, tobacco use is a leading cause of cancer and of death from cancer. NCI explains that tobacco products and secondhand smoke contain many chemicals that damage DNA — of the more than 7,000 chemicals in tobacco smoke, at least 250 are known to be harmful, and at least 69 can cause cancer.

NCI states that tobacco use causes many types of cancer, including cancers of the lung, larynx (voice box), mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, and cervix, as well as acute myeloid leukemia. NCI is direct that there is no safe level of tobacco use, and that people who use smokeless tobacco (snuff or chewing tobacco) also have increased risks of cancers of the mouth, esophagus, and pancreas.

The good news about quitting

NCI's message about quitting is genuinely hopeful. It states that people who quit smoking, regardless of their age, have substantial gains in life expectancy compared with those who continue to smoke. NCI also notes that quitting smoking at the time of a cancer diagnosis reduces the risk of death. In other words, it is never too late to benefit.

NCI offers free, confidential help through its quitline at 1-877-44U-QUIT (1-877-448-7848) and online counseling. Quitting is hard, and support genuinely helps — you can learn more on our quitting smoking page. If you are thinking about your overall cancer risk, our free screening check-up tool is a calm place to start.

How to take part

• If you use tobacco, World No Tobacco Day is a good moment to ask about quitting smoking and available support.
• Protect others from secondhand smoke, which NCI classifies as a known human carcinogen.
• Talk with young people about tobacco and nicotine before habits form.
• Share NCI's message that quitting benefits health at any age.

Questions to ask a healthcare team

• What quit-smoking methods or medicines might work best for me?
• How can I handle nicotine withdrawal and triggers?
• Given my tobacco history, are there screenings I should consider?
• How can I protect my family from secondhand smoke?