What Is Lung Cancer?

Lung cancer occurs when cancerous cells grow in the lung tissue and spread to surrounding lymph nodes and the blood.

Lung cancer happens when cancerous cells grow in the lung. Abnormal growth of the cancerous cells usually starts in the alveoli (tiny sacs in the lungs that help you breathe in oxygen) or the lining of the bronchi (tubes that carry air to your lungs).

Later, those cells can spread to the smaller branches of the bronchi (bronchioles) or the tiny air sacs at the end of those branches (alveoli). Lung cancer can invade the surrounding body tissue, lymph nodes, and bloodstream as the disease progresses.

Unfortunately, early symptoms of lung cancer can go unnoticed. As the condition progresses, you may have difficulty breathing, a persistent cough, or coughing up blood. Treatment depends on your type (either non-small cell or small cell lung cancer), what stage of cancer you are in, and the size and location of the tumor.

Lung cancer is the third most common cancer in the United States. More than 230,000 people are diagnosed annually. The disease claims more than 130,000 lives every year, accounting for nearly 25% of all cancer deaths.

Smoking is the leading risk factor for lung cancer. Healthcare providers recommend quitting smoking to lower your risk of lung cancer. Continuing to smoke after you develop lung cancer can also worsen you condition more quickly. Smoking can be a hard habit to break. So, as you work on using less tobacco, other lifestyle changes may help.

Types of Lung Cancer

Healthcare providers classify lung cancer into non-small cell lung cancer (NSCLC) or small cell lung cancer (SCLC). NSCLC usually spreads slower than SCLC.

Non-Small Cell Lung Cancer (NSCLC)

NSCLC is the most common form of lung cancer. NSCLC makes up about 80% to 85% of all cases.

There are three primary types of NSCLC: Adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Adenocarcinoma is the most common type of lung cancer. While smoking causes almost 90% of all NSCLC cases, adenocarcinoma is the most common type of lung cancer among non-smokers.

Small Cell Lung Cancer (SCLC)

SCLC generally accounts for about 15% of lung cancer diagnoses. Tobacco use almost always causes SCLC.

SCLC can spread to your brain, liver, and bones very quickly. There are two types of SCLC: Small cell carcinoma (also known as oat cell cancer) and combined small-cell lung carcinoma (a rare form of SCLC).

Lung Cancer Symptoms

Lung cancer can occur without any early warning signs. Your healthcare provider may detect the cancer accidentally (say, if you have a chest x-ray for another reason) before you develop symptoms.

But in most cases, symptoms develop after lung cancer progresses into an advanced stage. Most people have chest-related symptoms, like:

  • Chest pain
  • Persistent or worsening cough
  • Trouble breathing
  • Coughing up blood
  • Hoarse voice
  • Persistent infections (like bronchitis and pneumonia)
  • Wheezing

Lung cancer can affect other body parts if the cancerous cells spread. Symptoms may include:

  • Bone pain
  • Headache
  • Fatigue and weakness
  • Yellowing of the skin and eyes (if the cancer spreads to the liver)
  • Swollen lymph nodes
  • Unexplained weight loss

What Causes Lung Cancer?

Sometimes, your genes can increase your risk of lung cancer. Genetic changes, or mutations, may prompt healthy cells to grow and multiply too quickly.

Most of the time, mutations result from lifestyle and environmental factors. The most significant risk factor is long-term smoking. People who smoke may be up to 30 times more likely to get lung cancer than those who don't use tobacco.

But smoking is not the only cause. Other risk factors may include:

  • Secondhand smoke
  • Family history of lung cancer
  • Arsenic in drinking water
  • Exposure to radon, radiation, air pollution, and certain chemicals like asbestos
  • Taking beta-carotene supplements if you smoke

How is Lung Cancer Diagnosed?

Getting tested for lung cancer can feel scary. If your healthcare provider suspects you may have lung cancer, they will likely ask about your lifestyle habits. They may also ask about your family medical history and perform a physical exam.

Your healthcare provider may perform tests to confirm or rule out lung cancer. Some common diagnostic tools include:

  • Imaging tests: Chest x-rays, CT scans, MRIs, or PET scans take detailed pictures of your lungs to see if cancer cells are present.
  • Bone scan: This scan can examine if cancer cells have spread to your bones.
  • Sputum cytology: A type of test that asks you to cough up a sample of your mucus and tests the mucus for cancerous cells.
  • Thoracentesis: This procedure removes a sample of the fluid around the lungs to determine the cause of fluid build-up in your lungs.
  • Needle or core biopsy: A standard diagnostic test that uses a needle to take a sample of your lung tissue to check for cancer cells.
  • Bronchoscopy: This exam is a common way to take a biopsy of your lungs and helps your healthcare provider search for tumors or blockages in your airways.

Often, your healthcare provider will use more than one type of test before making an official diagnosis.

Stages of Lung Cancer

Your healthcare provider will stage the disease if you receive a lung cancer diagnosis. 

The stages of NSCLC include: 

  • Stage 0: Also known as carcinoma in situ (CIS), stage 0 is the earliest stage of NSCLC. In stage 0, cancerous cells grow in the lining of the alveoli or air passages but have not spread into the lung tissues.
  • Stage I: The tumor in your lung is less than three centimeters in diameter. Cancerous cells have not spread to the lymph nodes or other body parts.
  • Stage II: The tumor may be larger than three centimeters in diameter. Cancerous cells may have spread to nearby lymph nodes but not other body parts. 
  • Stage III: Cancerous cells have spread to the lymph nodes. Most commonly, cancerous cells invade the lymph nodes in the mediastinum, or the area in between your lungs.
  • Stage IV: The tumor may be any size in diameter. Cancerous cells have spread to the tissue that lines your lungs. In some cases, your healthcare provider may find cancerous cells in nearby or distant body parts.

The stages of NSCLC are further broken down (for example, stage IIA) based on the size of the tumor and whether it's spread to the lymph nodes or other body parts.

SCLC, on the other hand, is divided into just two stages: limited and extensive. Limited SCLC occurs when the cancer is contained in the chest area. Extensive SCLC spreads beyond the lungs and into areas of the body that radiation therapy cannot treat.

Treatments for Lung Cancer

If you receive a lung cancer diagnosis, your healthcare provider will work with you to choose the right treatment. You may also work with an oncologist, a healthcare provider specializing in cancer. The goal of treatment is to get rid of cancerous cells and achieve remission.

Your treatment may depend on your type of lung cancer, stage, and overall health. Common treatments may include:

  • Surgery: If you are in an early stage of lung cancer, surgery can help remove lobes, or sections, of the lung depending on the size and location of the tumor.
  • Radiation therapy: This treatment uses high-energy radiation to kill cancer cells and helps shrink tumors or eliminate them. There are several types, including stereotactic body radiation therapy—which can treat early-stage NSCLC and SCLC.
  • Chemotherapy: Your healthcare provider may administer chemotherapy orally or intravenously (through a vein in your arm) which can search for and kill cancer cells in your body.
  • Targeted therapy: Like chemotherapy, these drugs target cancer cells to prevent them from growing and spreading. Target therapy is generally used more often for treating SCLC than NSCLC.
  • Immunotherapy: This treatment uses drugs that strengthen and trigger your immune system to attack cancer cells.
  • Cryosurgery: A newer type of treatment, cryosurgery uses technology to freeze and kill cancer cells.
  • Palliative care: This form of care is an interdisciplinary approach. A team of different healthcare providers help you manage physical symptoms, tend to your emotional health, and provide you with resources to improve your overall quality of life.

How to Prevent Lung Cancer

Some risk factors for lung cancer, like genetics, are beyond your control. But you can make some lifestyle changes to decrease your risk.

Smoking is the cause of many lung cancers. Quitting smoking—cigarettes, cigars, and pipes—may help lower your risk. But smoking is a difficult habit to kick. In the meantime, you can try other lifestyle changes to reduce your risk, like:

  • Try to minimize exposure to secondhand smoke: Inhaling secondhand smoke, or smoke caused by someone else's cigarettes, is not something you can always control. Some ways to avoid exposure to secondhand smoke are to stay away from indoor public places (like restaurants) that still allow smoking. Also, ask people not to smoke in your car or home.
  • Avoid radon exposure: Radon is a colorless, odorless gas that forms when uranium in soil breaks down and builds up in your home. Radon commonly forms in basements. You can buy an at-home test kit or hire a professional to test for radon.
  • Eat nutritious foods: Maintaining a balanced diet that limits high-fat or highly-processed foods can help lower your risk.
  • Get annual lung cancer screenings: Annual screenings will not prevent lung cancer. But early screenings can help diagnose the disease before it progresses. Yearly screenings can help you get early treatment and reduce your risk of dying from lung cancer. Talk to your healthcare provider about whether you are eligible for annual screenings—this may depend on your age and history of smoking.

Co-Occurring Conditions

Evidence suggests respiratory (relating to the lungs) and cardiovascular (relating to the heart) diseases may be common in people with lung cancer.

Respiratory diseases may damage the lungs and cause trouble breathing. For example, smoking is a common risk factor for chronic obstructive pulmonary disease (COPD), a condition that can block the airways in your lungs. People with COPD are more likely to develop lung cancer than others.

Cardiovascular diseases are also common among people who have lung cancer due to smoking. People with lung cancer may have heart problems because of long-term tobacco use.

Living With Lung Cancer

Incorporating healthy behaviors into your lifestyle, such as eating healthy foods and getting regular exercise, can help improve your quality of life as you undergo treatments for lung cancer.

Even with treatment, having lung cancer can feel scary, frustrating, and isolating. You might be feeling some common side effects from your treatment which can include fatigue, nausea, vomiting, stress, anxiety, and depression. Living with lung cancer is not easy, but these options may enhance your quality of life:

  • Get good sleep and taking rest throughout the day
  • Go on walks or do light to moderate exercising
  • Partake in hobbies and activities
  • Eating nutritious foods that you enjoy
  • Stay hydrated with water
  • Try deep-breathing, relaxation, or massage techniques to help reduce stress
  • Spend time with family or friends
  • Ask your loved ones for help with daily tasks
  • Talk to your healthcare provider or reach out to a mental health professional if you need additional support

A Quick Review

Lung cancer begins as an overgrowth of abnormal cancerous cells that line the airways or another part of the lung. Lung cancer can invade the surrounding body tissue, lymph nodes, and bloodstream as the disease progresses. 

Smoking is the leading risk factor for lung cancer, but a variety of lifestyle changes, such as reducing tobacco use, can help you lower your risk of developing this condition. If you receive a diagnosis for lung cancer, there are several treatment options that your care team may offer, like chemotherapy, radiation, or palliative care.

Living with lung cancer is not easy and can often make you feel anxious or afraid. It's OK to feel this way. However, it's important to note that you are not alone in your diagnosis. Aside from treatment, getting rest, staying active with exercise or hobbies, and spending time with your loved ones during this journey can improve your overall quality of life.

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Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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