By Anna Giorgi 

 Medically reviewed by Gagandeep Brar, MD

Lung cancer is cancer that starts in your lungs. It is the leading cause of cancer death among men and women.1

Finding lung cancer early before it spreads improves your chances of beating the disease. Certain groups are advised to have routine lung cancer screenings to improve their chances of finding the problem early.

This article describes lung cancer types, symptoms, causes, diagnosis, stages, and treatments.

South_agency / Getty Images

Types of Lung Cancer

There are several types of lung cancer. The main types of lung cancer look, grow, and spread differently. Lung cancers are classified by the type of cell in which the cancer began.

Small Cell Lung Cancer

Small cell lung cancer accounts for up to 15% of all lung cancers. It comprises smaller-sized cells that grow and spread quickly. This type of lung cancer often originates in the bronchi near the center of your chest.2

The two types of small cell lung cancer are:3

• Small cell carcinoma: Small cell carcinoma is the most common type of small cell lung cancer. Its tumor cells look flat under a microscope.

• Combined small cell carcinoma: Combined small cell carcinoma involves tumors comprised of small cell carcinoma cells and non-small cell lung cancer cells.

Non-Small Cell Lung Cancer

Up to 85% of lung cancers are non-small cell lung cancers. It is the most common type of lung cancer. Non-small cell lung cancer usually grows and spreads slower than small cell lung cancer.4

There are several types of non-small lung cancer that originate from different types of lung cells. They include the following:

• Adenocarcinoma: Adenocarcinomas start in the cells that normally secrete substances like mucus and help us breathe. They are often found in the outer region of your lungs.5

• Squamous cell carcinoma: Squamous cell carcinomas are usually found in cells in the tissues in the center of your lung next to a bronchus, one of the air tubes that lead from the trachea (windpipe) to the lungs.6

• Large cell carcinoma: Large cell carcinomas originate in the cells that comprise the outer lining of your lungs. It is the most likely subtype of non-small cell lung cancer to spread.7

Other Types of Cancer in the Lungs

In addition to the main types of lung cancer, the following tumors can occur in your lungs:

Lung carcinoid tumors: Lung carcinoid tumors originate in neuroendocrine cells, a special type of lung cell. Most of these rare tumors grow slowly.8

Other lung tumors: The following types of lung cancers are treated differently from other, more common lung cancers:

• Adenoid cystic carcinomas

• Lymphomas

• Sarcomas

• Benign lung tumors

Cancers that spread to the lungs: Cancers that originate in other organs like the kidney, breast, pancreas, or skin, can metastasize to the lungs but they are not lung cancers. Treatment for these cancers is based on the primary site where cancer started.

Lung Cancer Symptoms

Lung cancer symptoms often go undetected in the early stages of the disease. Symptoms usually don't occur until the disease spreads.9

When they appear, lung cancer symptoms are often ignored or attributed to another condition because they are not unique to lung cancer. As a result, it is common for people to wait to consult a healthcare provider until symptoms worsen and the disease spreads.

Early Signs of Lung Cancer

Early signs of lung cancer can often appear to be other conditions. However, waiting to get a diagnosis could jeopardize your treatment options. The American Cancer Society advises that you consult your healthcare provider if you experience any of the following early signs of lung cancer:9

• A cough that persists or worsens

• Blood or rust-colored mucus/phlegm in your cough

• Chest pain that worsens with coughing, deep breathing, or laughing

• Shoulder pain

• Loss of appetite

• Unexplained weight loss

• Wheezing

• Shortness of breath

• Hoarseness or changes in voice

• Feeling tired or weak

• Persistent lung infections like bronchitis (inflammation of the bronchi walls) and pneumonia that don't improve or keep occurring

Late Symptoms

As cancer spreads, it can affect other parts of your body and can cause any of the following symptoms:109

• Bone pain, especially in the hips or back

• Headaches or seizures

• Weakness, numbness, or swelling of an arm or leg

• Dizziness/balance problem

• Jaundice (yellowing of the eyes and skin)

• Swelling of lymph nodes in the neck or above the collarbone

• Eyelid drooping or weakness

• Difficulty swallowing

• Facial paralysis (not being able to move the muscles of the face) or swelling

How Long Can You Have Lung Cancer Without Knowing?

Most people with lung cancer can live with the disease for months or years before they realize that they are ill. Obvious physical changes usually don't occur until the disease progresses.11

What Causes Lung Cancer?

There are several potential causes of lung cancer. It can also occur without a clear understanding of its cause.

Cigarette smoking ranks as the leading cause of lung cancer. It accounts for up to 90% of lung cancer cases. Smoking cigarettes makes you 15 to 30 times more likely to develop lung cancer than someone who doesn't smoke.12

The following characteristics can also increase your risk for lung cancer:

• Smoking other types of tobacco like pipes or cigars

• Breathing secondhand smoke from cigarettes, pipes, or cigars

• Personal or family history of lung cancer

• Exposure to the following substances at home or work:

• Radon

• Asbestos

• Arsenic

• Diesel exhaust

• Silica

• Chromium

• Radiation therapy to the chest

While smoking is a known cause of lung cancer, there is no clear evidence that some other practices, like electronic cigarettes (e-cigarettes) or marijuana, cause lung cancer. However, both vaping and smoking can cause damage to your lungs and may increase your risk of lung damage and other diseases, potentially increasing your risk of lung cancer.1314

How Smoking Causes Lung Cancer

Smoking ranks as the leading cause of lung cancer, causing 85% of lung cancer cases. Research indicates that smoking causes lung cancer by creating cell mutations from the carcinogens contained in cigarette smoke. When cells develop cancerous mutations, they continue to divide and grow abnormally.

How Is Lung Cancer Diagnosed?

Getting an accurate lung cancer diagnosis is key to getting the right lung cancer treatment as early as possible. Your healthcare uses the following tests to make a diagnosis:

Physical Examination:

A physical examination includes taking a thorough medical history and family history. Your healthcare provider determines your risk of lung cancer and investigates your symptoms.

Imaging

Imaging tests use X-rays, sound waves, magnetic fields, or radioactive substances to allow your healthcare provider to see the inside of your body. The following types of imaging tests are used:15

• Chest X-ray; A chest X-ray is the first test performed when lung cancer is suspected. It can show a lung mass of abnormal lung cells or a smaller spot called a lung nodule, though it can't determine whether the mass is benign or malignant.

• Computed tomography (CT) scan: A CT scan uses a series of X-rays to create a three-dimensional view of your lungs so your healthcare provider can look at the lungs from more than one angle.

• Magnetic resonance imaging (MRI): An MRI uses radio waves and strong magnets instead of X-rays to look for the spread of lung cancer.

• Positron-emission tomography (PET) scan: A PET scan uses the injection of a short-acting radioactive substance, called a radiotracer, which collects in cancer cells. A tunnel-like device is used to detect the emitted radiation and form pictures.

Lung Biopsy

When imaging tests indicate the presence of lung cancer, a lung biopsy is the next step in getting a diagnosis. This involves removing a tissue sample from the area where lung cancer is suspected. The following types of lung biopsy are used:

• Fine needle aspiration biopsy (uses a thin needle to extract lung tissue)

• Endoscopic ultrasound (uses a camera and sound waves to produce live images of your lungs and lymph nodes)

• Surgery

Bronchoscopy

A bronchoscopy uses a bronchoscope, a narrow tube with a light and camera on one end, to get an internal view of your respiratory system. It is inserted through the nose or mouth and guided down the windpipe.

Endobronchial Ultrasound

An endobronchial ultrasound combines bronchoscopy with an ultrasound probe to examine the mediastinum.

Thoracentesis

Thoracentesis involves using a large needle to remove a small amount of fluid from the pleural cavity, the space between your lungs.

Mediastinoscopy

A mediastinoscopy is a surgical procedure that uses a narrow scope, called a mediastinoscope, inserted through your chest wall to examine the mediastinum, the area between your lungs.

Labs and Tests

The following labs and tests are used to diagnose lung cancer:

• Complete blood count (CBC), which can determine changes in your blood caused by lung cancer

• Pulmonary function test, which determines lung capacity

• Sputum cytology, which involves using a microscope to examine a sample of sputum

Lung Cancer Screening

Lung cancer screening involves testing for a disease when thee aren't symptoms or history. The only recommended screening test for lung cancer is a low-dose computed tomography (CT) scan. The scan is noninvasive, painless, and highly accurate.16

Recommendations for Lung Cancer Screenings

The American Lung Association advises screening for lung cancer based on recommendations from the U.S. Preventive Services Task Force (USPSTF), a volunteer, independent panel of experts in evidence-based medicine and disease prevention.

Lung cancer screening with low-dose CT annually is advised for adults with all of the following characteristics:17

• Between the ages of 50 and 80 years

• A 20 pack-year smoking history (pack-years are calculated by multiplying the number of packs smoked per day times the number of years smoked)

• Currently smoke or have quit within the past 15 years

If you are included in this group, screening can cease if you have not smoked for 15 years or have a health problem that limits your life expectancy or your eligibility for lung surgery.

Lung Cancer Stages

Lung cancer staging defines if and how much your lung cancer has spread. It helps your healthcare providers determine your treatment plan. It is easier to treat lung cancer at an early stage than when the disease is in advanced stages.

Lung cancer staging is based on the following factors:18

• The location of your lung cancer

• The size and extent of your lung cancer tumors

• If and where the lung cancer spread

• Lymph node involvement

In the United States, lung cancer is staged using the American Joint Committee on Cancer’s TNM system which involves the following areas:18

• Size and tumor number (T)

• Lymph node involvement (N)

• If and to what extent the liver cancer has metastasized (M)

The two main types of lung cancer, non-small cell lung cancer and small lung cell cancer, are staged differently according to the following criteria:19

Non-Small Cell Lung Cancer Stages:

Stage 0 (carcinoma/tumor in-situ)

• Only present in the top lining of your lung

• No spread to other parts of your body

Stage 1

• Divided into substages 1A and 1B, based on tumor size

• No spread to the lymph nodes or other parts of your body

Stage 2

• Divided into substages 2A and 2B, based on tumor size, location, and lymph node involvement

• No spread to other parts of the body

Stage 3

• Divided into substages 3A, 3B, and 3C, based on tumor size, location, and how far it has spread

• Spread of cancer to the lymph nodes in the mediastinum

Stage 4

• The most advanced form of lung cancer

• Cancer has spread to the lining of your lung or other areas of your body

Small Cell Lung Cancer Stages

Limited stage:

• Lung cancer in only one lung

• With or without the spread to the lymph nodes in your mediastinum

Extensive stage:

• Lung cancer spread from the affected lung to the opposite lung or distant organs

The formal stage of your lung cancer doesn't change over time, even if your cancer improves or progresses. Rarely, cancer might be restaged after a period of remission.

Lung Cancer Treatment

Your options for lung cancer treatment are determined by your lung cancer stage, lung cancer type, and treatment goals. Depending on your circumstances, you may need more than one type of treatment.

Surgery

Lung cancer surgery involves removing portions of your lung. This procedure is regarded as the best option when lung cancer is limited to one area and hasn't spread. One of the following techniques is used:20

• Pneumonectomy: Removal of the entire affected lung

• Lobectomy: Removal of one of the sections, or lobes) of an affected lung

• Wedge resection: Removal of the tumor and a wedge-shaped area of the lung tissue surrounding the tumor

• Sleeve resection: Removal of a lobe and part of the bronchus

• Segmentectomy: Removal of a segment of a lobe that takes less tissue than a lobectomy but more tissue than a wedge resection

Radiation

Radiation therapy for lung cancer uses powerful, high-energy X-rays to stop the growth or kill cancer cells from outside your body to kill cancer cells.21

Chemotherapy

Chemotherapy for lung cancer involves the intravenous administration of drugs to kill or stop the growth of cancer cells,22

Immunotherapy

Immunotherapy uses the abilities of your body's immune system, which protects you from foreign agents, to help it recognize cancer cells and kill them.23

Targeted Drug Therapy

Targeted drug therapy uses treatments that interrupt the growth and normal function of cancer cells while reducing damage to healthy cells.24

Radiofrequency Ablation

Radiofrequency ablation is an image-guided technique that uses high-energy radio waves to heat a tumor and destroy cancer cells.

Complications of Lung Cancer

There are many potential complications of lung cancer. These problems can occur as a result of disease progression or the therapies used to treat the disease.

Common complications of lung cancer include the following:

• Chemotherapy-induced infection: Chemotherapy reduces the number of white blood cells that fight infection, making your body susceptible to neutropenia, a condition that increases your risk of infections like pneumonia and sepsis.25

• Malignant pleural effusion: A malignant pleural effusion occurs when there is a buildup of fluid that contains cancer cells in the pleural cavity, the area between the membranes that line your lungs.26

• Hypercalcemia: Hypercalcemia, abnormally high calcium levels in your blood, occurs when cancer spreads to your bones.27

• Depression: While depression is common in many types of cancer, people with lung cancer may have a higher risk of depression because of the disease's stigma or a likelihood of a poor prognosis.28

• Malignant pericardial effusion: Malignant pericardial effusion occurs when the pericardium, the sac surrounding the heart, becomes filled with extra fluid.29

• Blood clots: Blood clots in the pelvis or legs can develop in the deep veins of your arms or legs and cause severe swelling and pain.30

• Pulmonary hemorrhage: A pulmonary hemorrhage is a sudden bursting of a major blood vessel in your lungs. It occurs when a tumor infiltrates a blood vessel and weakens it.31

• Spinal cord compression: Spinal cord compression can develop when lung cancer spreads to the bones of your spine, making them weaken and at risk of collapsing.32

• Superior vena cava syndrome: Superior vena cava syndrome is a group of problems that occur when tumors in the upper portion of your lungs press directly on the superior vena cava, the large vein that returns blood away from your upper body to your heart.33

Can You Prevent Lung Cancer?

Lung cancer can't always be prevented. Some cases of lung cancer occur in people who don't smoke or have any risk factors. However, taking the following steps can help lower your risk of lung cancer:34

• If you smoke, quit. If you don't smoke, don't start.

• Avoid exposure to secondhand smoke.

• Avoid exposure to radon by checking your home.

• Avoid or limit exposure to cancer-causing substances at home and at work.

• Eat a healthy diet that includes plenty of fruits and vegetables.

• Exercise regularly.

• Get screened for lung cancer as advised.

Outlook for Lung Cancer

Your lung cancer prognosis is a forecast or prediction of the way your healthcare provider expects your lung cancer and treatment to evolve. While the outlook for your lung cancer is based on the details of your condition, it is calculated on the experiences of large groups of people over many years, not individual cases. Your experience with lung cancer can differ from the prognosis you receive.

Your prognosis depends on the following factors:35

• Stage of lung cancer

• The type of cancer and where it is in your body

• Weight loss

• Performance status, how well you can do your daily activities

• Sex

• Age

• Overall health

• Genetic changes to your cancer cells

The five-year survival rate for lung cancer is 56% for cases diagnosed when the cancer is limited to your lungs. However, because lung cancer often begins without symptoms, only 16% of lung cancer cases are identified in the early stage of the disease.36

Living With Lung Cancer: Support and Resources

Dealing with a lung cancer diagnosis requires more than medical care. Research indicates that people with lung cancer experience poor quality of life and an increased rate of psychological distress.37

Having a strong support system can make a difference in your physical and mental health. Accept the help of family and friends who are willing to handle everything from meal preparation to driving you to and from appointments. Trying to do everything on your own can leave you feeling overwhelmed and exhausted.

If you're feeling overwhelmed, ask for a palliative care support visit. This involves meeting with a team of specialists, including a social worker, a nurse, and a healthcare provider, who can address the full range of concerns involved in your cancer treatment.

Some of the most valuable resources are those that involve others who understand what you are experiencing. Check out lung cancer social media blogs by people who are sharing their cancer journeys.

You can include an online or local cancer support group. You may benefit most from being with people who understand what you are experiencing. Some options for support groups include the following organizations:

• LUNGevity Support Community

• Inspire: Lung Cancer Survivors Community

• CancerCare

• The Cancer Survivors Network

Summary

Lung cancer can be a severe and deadly type of cancer. It ranks as the leading cause of cancer-related deaths.

Lung cancer most often affects people with a history of smoking. However, you can get this disease even if you don't smoke or have other known risk factors.

Since many people don't have symptoms until their lung cancer spreads to other parts of their body, lung cancer is often deadly and hard to treat. However, getting an early diagnosis can improve your chances of having the best outcomes.

While there are several treatment options, they are not always effective in killing this fast-moving disease. Lung cancer clinical trials may provide more options if current treatments are not helpful.

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By Anna Giorgi
Anna Zernone Giorgi is a writer who specializes in health and lifestyle topics. Her experience includes over 25 years of writing on health and wellness-related subjects for consumers and medical professionals, in addition to holding positions in healthcare communications.