# Does smoking cause lung cancer?

Source: https://oncologyistanbul.com/answers/does-smoking-cause-lung-cancer
Last updated: 2026-07-13

Yes. According to the U.S. National Cancer Institute, tobacco smoking is the most important risk factor for lung cancer, causing about 9 out of 10 cases in men and about 8 out of 10 cases in women. The risk rises with the number of cigarettes smoked per day and the number of years smoked, and people who smoke have about 20 times the risk of those who do not. Being exposed to secondhand smoke is also a risk factor. Quitting smoking lowers the risk, though it may never fall as low as a nonsmoker's. This is general information, not personal medical advice.

## Verify at
- [Lung Cancer Prevention (PDQ) — Patient Version](https://www.cancer.gov/types/lung/patient/lung-prevention-pdq) — National Cancer Institute (NCI) (checked 2026-07-13)
- [Tobacco (cancer risk)](https://www.cancer.gov/about-cancer/causes-prevention/risk/tobacco) — National Cancer Institute (NCI) (checked 2026-07-13)

Related: [Lung cancer treatment options](https://oncologyistanbul.com/cancers/lung)