Lung Cancer: Types, Symptoms, Causes, Treatments
Author: Disabled World (DW)
Updated/Revised Date: 3 Nov 2026
Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics
Synopsis
A thorough guide to lung cancer, covering the types, symptoms, causes such as smoking and radon, staging, diagnosis, and treatment options including chemotherapy.
At a Glance
- 1 - Radon gas is the second leading cause of lung cancer in America.
- 2 - Tobacco smoke contains more than 7,000 chemical compounds, many of them carcinogenic.
- 3 - About 28 percent of people with lung cancer in the United States survive at least five years.
- 4 - Yearly low-dose CT screening is recommended for adults aged 50 to 80 with a 20 pack-year smoking history who smoke now or quit within 15 years.
Topic Definition
- Lung Cancer
Lung cancer, also called carcinoma of the lung or pulmonary carcinoma, is a malignant tumor caused by the uncontrolled growth of abnormal cells in the tissues of the lung. Most lung cancers - roughly 90 to 95 percent - begin in the lining cells of the bronchi and bronchioles, the airways that branch through the lungs and end in the tiny air sacs where oxygen and carbon dioxide are exchanged. Because these malignant cells can metastasize early, spreading through the bloodstream or lymphatic system to organs such as the liver, brain, bones, and adrenal glands, lung cancer is both life-threatening and among the hardest cancers to treat. It is generally divided into two main groups: small-cell lung cancer, which is aggressive and strongly tied to smoking, and the more common non-small-cell lung cancer, which includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Smoking is the leading cause, though radon gas, asbestos, air pollution, family history, and certain lung diseases also raise the risk.
Overview
Defining Lung Cancer
Lung cancer, also known as carcinoma of the lung or pulmonary carcinoma, is a malignant tumor caused by the uncontrolled growth of abnormal cells in the tissues of the lung. It is one of the most common cancers in the world and the leading cause of cancer death in both men and women, in the United States and worldwide. The American Cancer Society estimates that about 229,410 people in the United States will be diagnosed with lung cancer in 2026 and about 124,990 will die from it, more than from colorectal and pancreatic cancers combined [Siegel et al., 2026].
Lung cancer can spread (metastasize) through the bloodstream or lymphatic system, often early in its course, which is one reason it is hard to treat. It most often spreads to the lymph nodes, liver, brain, bones and adrenal glands. Cancer that starts somewhere else and spreads to the lungs, such as metastatic Prostate Cancer, is not lung cancer and is treated as the original type of cancer.
How the Lungs Work
The lungs bring oxygen from the air into the blood and remove carbon dioxide. The right lung has three lobes and the left lung has two, plus a small section called the lingula. Air reaches the lungs through the windpipe (trachea), which divides into two main airways (bronchi). These branch into smaller and smaller airways (bronchioles) that end in tiny air sacs (alveoli), where gases are exchanged. A thin layer of tissue called the pleura covers the lungs and lines the chest wall.
Most lung cancers begin in the cells lining the bronchi and bronchioles, which is why lung cancer is sometimes called bronchogenic carcinoma. Cancer that begins in the pleura is a different disease called Mesothelioma.
Who Gets Lung Cancer?
Lung cancer is mainly a disease of older adults. Most people are diagnosed at 65 or older, and very few are diagnosed before age 45. Lung cancer was uncommon before the 1930s and rose sharply as cigarette smoking spread. Deaths from lung cancer in the United States have fallen for decades as fewer people smoke and treatment improves. Lung cancer has caused more deaths among American women than Breast Cancer since the late 1980s.
Worldwide, there were almost 2.5 million new cases of lung cancer and about 1.8 million deaths in 2022, making it the most common cancer and the leading cause of cancer death [Bray et al., 2024].
Causes and Risk Factors
- Smoking: About 80 to 90 percent of lung cancer deaths in the United States are linked to cigarette smoking. Tobacco smoke contains more than 7,000 chemicals, about 70 of which can cause cancer. The risk rises with the number of cigarettes smoked and the number of years of smoking, often measured in pack-years (packs per day multiplied by years smoked). Cigar and pipe smoking also raise the risk. Quitting at any age lowers the risk, and after about 15 years without smoking, the risk falls a long way, although it stays higher than for someone who never smoked [Centers for Disease Control and Prevention, n.d.].
- Secondhand smoke: Breathing other people's smoke causes about 7,300 lung cancer deaths each year among Americans who do not smoke.
- Radon: Radon is a natural, invisible and odorless radioactive gas that comes from uranium in soil and rock and can build up in homes. It is the second leading cause of lung cancer in the United States, causing about 21,000 deaths a year, according to the U.S. Environmental Protection Agency. About 1 in 15 U.S. homes has a high radon level, and simple home test kits can detect it.
- Asbestos and other workplace exposures: Asbestos fibers can stay in the lungs for life. People who worked with asbestos have a higher risk of lung cancer, and those who also smoke have a risk fifty to ninety times that of a non-smoker. Exposure to arsenic, chromium, nickel, diesel exhaust and silica also raises the risk.
- Air pollution: Long-term exposure to outdoor air pollution, especially fine particles, raises the risk of lung cancer, including in people who have never smoked.
- Family history and genes: Lung cancer is more likely in relatives of people who have had it, whether or not they smoke.
- Lung disease and past lung cancer: Chronic obstructive pulmonary disease (COPD) and lung scarring raise the risk, and people who have had lung cancer are more likely to develop a second one.
- Past radiation to the chest: Radiation therapy for other cancers, such as breast cancer or lymphoma, can raise the risk later in life.
About 10 to 20 percent of lung cancers occur in people who have never smoked. These cancers are more common in women and are often linked to radon, secondhand smoke, air pollution or gene changes such as EGFR mutations.
Types of Lung Cancer
Lung cancers are divided into two main types, which grow and spread differently and are treated differently:
- Non-Small Cell Lung Cancer (NSCLC): the most common type, making up most lung cancers. Its main subtypes are adenocarcinoma, the most common type in both smokers and non-smokers; squamous cell carcinoma, which usually starts in the central airways and is closely linked to smoking; and large cell carcinoma, a less common, fast-growing type.
- Small-Cell Lung Cancer (SCLC): about 13 percent of lung cancers. It grows and spreads quickly, is almost always linked to smoking, and has often spread by the time it is found. It is sometimes called oat-cell carcinoma because of its look under a microscope.
- Other tumors: Lung carcinoid tumors are slow-growing neuroendocrine tumors that are not linked to smoking and can often be removed by surgery. Rare cancers can also start in the supporting tissues of the lung.
Signs and Symptoms of Lung Cancer
Early lung cancer often causes no symptoms, and many cancers are found by chance on a chest X-ray or CT scan done for another reason. When symptoms do occur, they can include:
- A cough that does not go away or gets worse
- Coughing up blood or rust-colored phlegm
- Chest pain that is often worse with deep breathing, coughing or laughing
- Shortness of breath, wheezing or hoarseness
- Repeated bouts of pneumonia or bronchitis
- Loss of appetite, unexplained weight loss and fatigue
Cancer that has spread can cause bone pain, headaches, seizures, weakness or numbness, yellow skin and eyes, or lumps in the neck. A tumor at the top of the lung (Pancoast tumor) can cause shoulder and arm pain, and some lung cancers, especially small cell lung cancer, make hormone-like substances that cause other problems (paraneoplastic syndromes), such as high calcium levels or Cushing's syndrome. See a doctor if you have a cough that will not go away, cough up blood, or have any of these symptoms.
Screening
The U.S. Preventive Services Task Force recommends a yearly low-dose CT scan for adults aged 50 to 80 who have a 20 pack-year smoking history and currently smoke or quit within the past 15 years. Screening finds lung cancer at an earlier, more treatable stage and lowers the risk of dying from it.
Diagnosing Lung Cancer
Doctors use a physical exam and history, imaging tests and a biopsy to diagnose lung cancer:
- Imaging: chest X-ray, CT scan, PET-CT scan to look for spread, and MRI of the brain.
- Biopsy: a tissue sample is taken by bronchoscopy, often with ultrasound guidance through the airway (endobronchial ultrasound), by a needle passed through the chest wall under CT guidance, or by surgery. Fluid around the lung can be sampled with a needle (thoracentesis).
- Biomarker testing: the tumor is tested for gene changes such as EGFR, ALK, ROS1, KRAS G12C, BRAF, MET, RET and HER2, and for the protein PD-L1. These results guide the choice of targeted drugs and immunotherapy.
- Blood and breathing tests: to check general health, liver and bone involvement, and how well the lungs work before treatment.
Stages of Lung Cancer
Non-small cell lung cancer is staged from I to IV with the TNM system, based on the size of the tumor (T), whether it has spread to lymph nodes (N) and whether it has spread to distant organs (M). In stage I the cancer is small and confined to the lung; in stages II and III it is larger or has spread to lymph nodes in the chest; in stage IV it has spread to the other lung, the lining around the lungs or heart, or distant organs. Small cell lung cancer is often described as limited stage (confined to one side of the chest) or extensive stage (spread more widely).
Treatment of Lung Cancer
Treatment depends on the type and stage of the cancer, the results of biomarker tests, and the person's overall health and wishes. Most people receive a combination of treatments:
- Surgery: removing a lobe of the lung (lobectomy) or a smaller part is the main treatment for stage I and II non-small cell lung cancer, often done through small incisions.
- Radiation therapy: high-energy beams kill cancer cells. Stereotactic body radiation therapy (SBRT) delivers very precise, high doses in a few sessions and is an option for small tumors in people who cannot have surgery. Radiation therapy is also combined with chemotherapy for stage III cancer and used to relieve symptoms.
- Chemotherapy: platinum-based drug combinations are used before or after surgery, with radiation, or for advanced cancer, often together with immunotherapy.
- Targeted therapy: for tumors with certain gene changes, drugs taken by mouth, such as osimertinib for EGFR mutations or alectinib and lorlatinib for ALK changes, often work better and with fewer side effects than chemotherapy.
- Immunotherapy: checkpoint inhibitors such as pembrolizumab, nivolumab, atezolizumab and durvalumab help the immune system attack cancer cells. They are now a standard treatment for many people with non-small cell lung cancer, before or after surgery and for advanced disease, and for extensive-stage small cell lung cancer.
- Other treatments: procedures such as radiofrequency ablation, airway stents, and drainage of fluid around the lung can control the tumor or relieve symptoms. Palliative care helps with breathing problems, pain and other symptoms at any stage.
Small cell lung cancer is usually treated with chemotherapy and immunotherapy, often with radiation to the chest. Radiation to the head may be offered to prevent the cancer from spreading to the brain.
Lung Cancer Prognosis
The outlook depends mainly on the type and stage of the cancer at diagnosis. About 28 percent of people with lung cancer in the United States are alive five years after diagnosis, up from 15 percent in the mid-1990s, thanks to screening, targeted drugs and immunotherapy [Siegel et al., 2026]. Survival is much higher when the cancer is found early, while it is still in the lung, and lower when it has spread. Small cell lung cancer has a poorer outlook than non-small cell lung cancer.
Lung Cancer Facts and Statistics
- About 229,410 new cases and 124,990 deaths from lung cancer are expected in the United States in 2026 [Siegel et al., 2026].
- Lung cancer causes more deaths than any other cancer, in the United States and worldwide.
- About 80 to 90 percent of lung cancer deaths are linked to smoking, and about 10 to 20 percent of lung cancers occur in people who have never smoked.
- Radon is the second leading cause of lung cancer in the United States, causing about 21,000 deaths a year.
- Worldwide, there were almost 2.5 million new cases of lung cancer and about 1.8 million deaths in 2022 [Bray et al., 2024].
Frequently Asked Questions
Can non-smokers get lung cancer?
Yes, non-smokers can develop lung cancer, and about 10 to 20 percent of cases occur in people who have never smoked, often linked to radon, secondhand smoke, asbestos, air pollution, or genetics.
Is lung cancer hereditary?
Genetics can play a role, and lung cancer is more likely in both smoking and non-smoking relatives of people who have had the disease, though smoking and environmental exposures remain the leading causes.
How can I test my home for radon?
Radon is odorless and invisible, but it can be measured with easy to use home test kits, and reducing high levels can lower the risk of radon related lung cancer.
What is the survival rate for lung cancer?
Survival varies widely by type and stage, and overall about 28 percent of people with lung cancer in the United States survive at least five years after diagnosis, with early detection improving outcomes.
How is lung cancer different from mesothelioma?
Lung cancer begins in the lung tissue itself, while mesothelioma starts in the pleura, the thin lining covering the lungs and chest wall, and is strongly associated with asbestos exposure.
Does secondhand smoke really increase lung cancer risk?
Yes, passive smoking is an established risk factor, and non-smokers living with a smoker face about a 24 percent higher risk of developing lung cancer than those who do not.
What are the early warning signs of lung cancer?
Possible early signs include a persistent or worsening cough, coughing up blood, chest pain, shortness of breath, hoarseness, and unexplained weight loss, though some people have no symptoms at first.
Who should get lung cancer screening?
The US Preventive Services Task Force recommends a yearly low-dose CT scan for adults aged 50 to 80 who have a 20 pack-year smoking history and smoke now or quit within the past 15 years. Screening can find cancer early when it is easier to treat.
References
- Bray, F., et al. (2024). Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA: A Cancer Journal for Clinicians, 74(3), 229-263.
- Centers for Disease Control and Prevention. (n.d.). Lung cancer risk factors.
- Siegel, R. L., et al. (2026). Cancer statistics, 2026. CA: A Cancer Journal for Clinicians.
- U.S. Preventive Services Task Force. (2021). Screening for lung cancer: US Preventive Services Task Force recommendation statement. JAMA, 325(10), 962-970.
Curated and edited by Ian C. Langtree, Founder and Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team. Last updated: