Smoking causes the majority of lung cancers — both in smokers and in people exposed to secondhand smoke. But lung cancer also occurs in people who never smoked and in those who never had prolonged exposure to secondhand smoke. In these cases, there may be no clear cause of lung cancer.
How smoking causes lung cancer
Doctors believe smoking causes lung cancer by damaging the cells that line the lungs. When you inhale cigarette smoke, which is full of cancer-causing substances (carcinogens), changes in the lung tissue begin almost immediately.
At first your body may be able to repair this damage. But with each repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.
Types of lung cancer
Doctors divide lung cancer into two major types based on the appearance of lung cancer cells under the microscope. Your doctor makes treatment decisions based on which major type of lung cancer you have. The two general types of lung cancer include:
Sept. 25, 2015
- Small cell lung cancer. Small cell lung cancer occurs almost exclusively in heavy smokers and is less common than non-small cell lung cancer.
- Non-small cell lung cancer. Non-small cell lung cancer is an umbrella term for several types of lung cancers that behave in a similar way. Non-small cell lung cancers include squamous cell carcinoma, adenocarcinoma and large cell carcinoma.
- Non-small cell lung cancer. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed Aug. 27, 2015.
- Estimated new cancer cases and deaths by sex, U.S., 2015. American Cancer Society. http://www.cancer.org/research/cancerfactsstatistics/cancerfactsfigures2015/index. Accessed Aug. 27, 2015.
- Small cell lung cancer. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed Aug. 27, 2015.
- Niederhuber JE, et al., eds. Cancer of the lung. Abeloff's Clinical Oncology. 5th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2014. http://www.clinicalkey.com. Accessed Aug. 27, 2015.
- What you need to know about lung cancer. National Cancer Institute. http://www.cancer.gov/publications/patient-education/wyntk-lung-cancer. Accessed Aug. 27, 2015.
- Lung cancer prevention (PDQ). National Cancer Institute. http://www.cancer.gov/types/lung/patient/lung-prevention-pdq. Accessed Aug. 27, 2015.
- Aberle DR, et al. Reduced lung-cancer mortality with low-dose computed tomographic screening. New England Journal of Medicine. 2011;365:395.
- Detterbeck FC, et al. Diagnosis and management of lung cancer, 3rd ed.: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2013;143(suppl):7S.
- AskMayoExpert. Non-small cell lung cancer. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2015.
- AskMayoExpert. Small cell lung cancer. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2015.
- Cook AJ. Decision Support System. Mayo Clinic, Rochester, Minn. March 17, 2015.
- Cairns LM. Managing breathlessness in patients with lung cancer. Nursing Standard. 2012;27:44.
- Taking time: Support for people with cancer. National Cancer Institute. http://www.cancer.gov/publications/patient-education/taking-time. Accessed Aug. 27, 2015.
- Temel JS, et al. Early palliative care for patients with metastatic non-small-cell lung cancer. New England Journal of Medicine. 2010;363:733.