Lung cancer
Cancer - lung
Lung cancer is cancer that starts in the lungs.
The lungs are located in the chest. When you breathe, air goes through your nose, down your windpipe (trachea), and into the lungs, where it flows through tubes called bronchi. Most lung cancer begins in the cells that line these tubes.
There are two main types of lung cancer:
- Non-small cell lung cancer (NSCLC) is the most common type of lung cancer.
- Small cell lung cancer (SCLC) makes up about 20% of all lung cancer cases.
If the lung cancer is made up of both types, it is called mixed small cell/large cell cancer.
If the cancer started somewhere else in the body and spreads to the lungs, it is called metastatic cancer to the lung.
Cancer can affect just about any part of the body, from the colon to the pancreas. Some cancers grow quickly, while others grow more slowly and are easier to treat. But of all the different cancers out there, one of the deadliest is lung cancer. Let's talk today about lung cancer. Cancer starts when cells begin to grow uncontrollably and form tumors. In the case of lung cancer, the tumors start in the lungs. Sometimes cancer starts somewhere else in the body and then spreads to the lungs. In that case, it's called metastatic cancer to the lung. Metastatic means disease that has spread. There are two types of lung cancer. The most common, and slower-growing form is non-small cell lung cancer. The other, faster-growing form is called small cell lung cancer. The most common way to get lung cancer is to smoke cigarettes. The more cigarettes you smoke and the earlier you start smoking, the greater your risk is. Even being around someone who smokes and breathing in the secondhand smoke from their cigarettes increases your risk of getting lung cancer. Even though smoking makes you much more likely to get lung cancer, you don't have to smoke or be exposed to smoke to get the disease. Some people who have lung cancer never lit up a cigarette in their life. They have been exposed to cancer-causing substances like asbestos, diesel fumes, arsenic, radiation, or radon gas. Or, they may not have had any known lung cancer risks. The most common signs of lung cancer are a cough that won't go away, chest pain, shortness of breath, weight loss, and fatigue. But just because you have these symptoms it doesn't mean that you have don't have lung cancer. These can also be signs of other conditions, like asthma or a respiratory infection. If you do have these symptoms, see your doctor. A chest x-ray, MRI, or CT scan can view the inside of your lungs to look for signs of cancer or other diseases. What happens if you do have lung cancer? Doctors divide lung cancer into stages. The higher the stage, the more the cancer has spread. For example, a stage 1 cancer is small and hasn't spread outside of the lungs. A stage 4 cancer has spread to the other organs, such as the kidneys or brain. Depending upon the type and stage of your lung cancer, you may need surgery to remove part or all of your lung. Or, your doctor may recommend radiation or chemotherapy to kill cancer cells. If you have lung cancer, how well you do depends upon the stage of your disease and the type of lung cancer that you have. Early-stage cancers have the highest survival and cure rates. Late-stage cancers are harder to treat. Because lung cancer can be so deadly, prevention is key. The most important that thing you can do is to stop smoking, and avoid being around anyone who does smoke.
Causes
Lung cancer is the deadliest type of cancer for both men and women. Each year, more people die of lung cancer than of breast, colon, and prostate cancers combined.
Lung cancer is more common in older adults. It is rare in people under age 45.
Smoking causes most cases (around 90%) of lung cancer. The risk depends on the number of cigarettes you smoke each day and for how long you have smoked. Being around the smoke from other people (secondhand smoke) also raises your risk of lung cancer. The risk decreases with time after you stop smoking. But some people who have never smoked do develop lung cancer. There is no evidence that smoking low-tar cigarettes lowers the risk.
Research shows that smoking marijuana may help cancer cells grow. But there is no direct link between smoking marijuana and developing lung cancer.
Constant exposure to high levels of air pollution and drinking water that has a high level of arsenic can increase your risk of lung cancer. A history of radiation therapy to the lungs can also increase risk.
Working with or living near cancer-causing chemicals or materials can also increase the risk of developing lung cancer. Such chemicals include:
- Arsenic
- Asbestos
- Radon
- Chemicals such as uranium, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, and diesel exhaust
- Certain alloys, paints, pigments, and preservatives
- Products using chloride and formaldehyde
Symptoms
Early lung cancer may not cause any symptoms.
Symptoms depend on the type of cancer you have, but may include:
- Chest pain
- Cough that does not go away
- Coughing up blood
- Fatigue
- Losing weight without trying
- Loss of appetite
- Shortness of breath
- Wheezing
Other symptoms that may also occur with lung cancer, often in the late stages:
- Bone pain or tenderness
- Eyelid drooping
- Facial paralysis
- Hoarseness or changing voice
- Joint pain
- Nail problems
- Shoulder pain
- Swallowing difficulty
- Swelling of the face or arms
- Weakness
These symptoms can also be due to other, less serious conditions, so it is important to talk to your health care provider.
Exams and Tests
Lung cancer is often found when an x-ray or CT scan is done for another reason.
If lung cancer is suspected, your provider will perform a physical exam and ask about your medical history. You will be asked if you smoke. If so, you'll be asked how much you smoke and for how long you have smoked. You will also be asked about other things that may have put you at risk for lung cancer, such as exposure to certain chemicals.
When listening to your chest with a stethoscope, your provider may hear fluid around your lungs. This may suggest cancer.
Tests that may be done to diagnose lung cancer or to see if it has spread include:
- Bone scan
- Chest x-ray
- Complete blood count (CBC)
- CT scan of the chest and abdomen
- MRI of the chest
- Positron emission tomography (PET) scan
- Sputum test to look for cancer cells
- Thoracentesis (sampling of fluid buildup around the lung)
In most cases, a piece of tissue is removed from your lungs for examination under a microscope. This is called a biopsy. There are several ways to do this:
- Bronchoscopy combined with biopsy
- CT-scan-directed needle biopsy
- Endoscopic bronchoscopy ultrasound (EBUS) with biopsy
- Mediastinoscopy with biopsy
- Open lung biopsy
- Pleural biopsy
If the biopsy shows cancer, it may be checked for certain genetic changes that may lead to specific treatment. More imaging tests are done to find out the stage of the cancer. Stage means how big the tumor is and how far it has spread. Staging helps guide treatment and follow-up and gives you an idea of what to expect.
Treatment
Treatment for lung cancer depends on the type of cancer, how advanced it is, and how healthy you are:
- Surgery to remove the tumor may be done when it has not spread beyond nearby lymph nodes.
- Chemotherapy, immunotherapy, and targeted therapy use medicines to kill cancer cells and stop new cells from growing.
- Radiation therapy uses powerful x-rays or other forms of radiation to kill cancer cells.
The above treatments may be done alone or in combination. Your provider can tell you more about the specific treatment you will receive, depending on the specific type of lung cancer and what stage it is.
Support Groups
You can ease the stress of illness by joining a cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.
Outlook (Prognosis)
How well you do depends on how much the lung cancer has spread and whether the cancer cells have certain genetic changes that create target molecules in or on the cells.
When to Contact a Medical Professional
Contact your provider if you have symptoms of lung cancer, particularly if you smoke.
Prevention
If you smoke, now is the time to quit. If you are having trouble quitting, talk with your provider. There are many methods to help you quit, from support groups to prescription medicines. Also, try to avoid secondhand smoke.
If you are age 50 to 80 years and have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years, ask your provider about being screened for lung cancer by low-dose CT scan of your chest.
References
American Cancer Society website. Key statistics for lung cancer.
American Lung Association website. Lung cancer trends brief.
Araujo LH, Horn L, Merritt RE, Shilo K, Xu-Welliver M, Carbone DP. Cancer of the lung: non-small cell lung cancer and small cell lung cancer. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 69.
Centers for Disease Control and Prevention website. Health problems caused by secondhand smoke.
National Cancer Institute website. Non-small cell lung cancer treatment (PDQ) - health professional version.
National Cancer Institute website. Small cell lung cancer treatment (PDQ) - health professional version.
Pastis NJ, Gonzalez AV, Silvestri GA. Lung cancer: diagnosis and staging. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 76.
US Preventive Services Task Force website. Final recommendation statement: Lung cancer screening.
Version Info
Last reviewed on: 1/25/2022
Reviewed by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Internal review and update on 02/20/2024 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
