Cancer may seem complex. But at its core, cancer is simple. Normal cells grow and die when your body needs them to. Cancer is what happens when certain cells grow even though your body doesn’t need them.

In many cases, these cancerous cells form a lump or mass called a tumor. Since cancerous cells don’t act like normal cells, tumors can prevent your body from working correctly. Given time, they can also spread, or metastasize, to other parts of the body.

Lung cancer is cancer that starts in the cells that make up the lungs. It isn’t cancer that spreads to the lungs from other parts of the body. This is key because treatment is based on the original site of the tumor. For example: If a tumor begins in the breast and spreads to the lungs, it would be treated as metastatic breast cancer—not lung cancer.

The lungs are sponge-like organs in your chest. Their job is to bring oxygen into the body and to get rid of carbon dioxide. When you breathe air in, it goes into your lungs through your windpipe (trachea). The trachea divides into tubes called bronchi, which enter the lungs. These divide into smaller branches called bronchioles. At the end of the bronchioles are tiny air sacs called alveoli. The alveoli move oxygen from the air into your blood. They take carbon dioxide out of the blood. This leaves your body when you breathe out (exhale).

Your right lung is divided into 3 sections (lobes). Your left lung has 2 lobes.

There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Understanding the differences between these types may lessen anxiety about your diagnosis and treatment.

Lung cancer acts differently in different people. But when it spreads, it tends to go to the same places. First: lymph nodes in the center of the chest. It may also spread to lymph nodes in the lower neck.

Lymph nodes are small clusters of immune system cells.

During later stages, lung cancer may spread to more distant parts of the body, such as the liver, brain, or bones.

If you have questions about lung cancer, talk with your healthcare provider. They can help you understand more about this cancer. 

Studies have shown that low-dose CT (LDCT) scans can help detect lung cancer early in certain high-risk people. This specifically includes heavy smokers ages 55 to 74.

LDCT scans use X-rays to create detailed 3-D images of your lungs. They are totally painless and require no special preparation. All you do is lie down on a narrow table as it passes through a ring-shaped CT scanner. At most, you may be asked to hold your breath a few times during the test.

LDCT scans can spot abnormal areas that regular chest X-rays might miss. The benefit is significant: a lower risk of dying from lung cancer. Some potential downsides, however, include:

• Many abnormalities surfaced in LDCT scans do not turn out to be cancer. These findings can cause unnecessary anxiety.
• More tests may determine whether the abnormal area is cancer. Sometimes, these exams can lead to complications.
• Each scan uses a small amount of radiation.

Keep in mind: LDCT scans do not find all lung cancers. It’s also possible the cancers they do find may have already progressed to a later stage.

The U.S. Preventive Services Task Force (USPSTF) and other expert groups have created specific guidelines for who should get screened. They recommend yearly LDCT scans for people who are:

• Between the ages of 50 and 80 AND
• Current smokers, or former smokers who have quit in the past 15 years AND
• Have a 20-pack year history of smoking. A pack-year is the equivalent of smoking an average of one pack of cigarettes per day for a year. In other words, smoking a pack a day for 20 years equals 20 pack-years. Smoking two packs a day for 10 years also equals 20 pack-years.

The USPSTF says that screening can stop once a person has not smoked for 15 years or has a health problem that limits their life expectancy or their ability to have lung surgery.

Even if you meet all the testing criteria, it’s important to talk with your healthcare provider about your personal health and risk. Some questions to consider asking are:

• What are the limits and risks of screening? Understanding potential outcomes before you go for a screening may reduce feelings of fear or anxiety.

• Am I healthy enough to get a screening? The risks of screening outweigh the benefits for certain people. For example, if someone can’t have lung surgery to remove the cancer, screening may not be a good option.

• Where should I go for a lung cancer screening and treatment, if needed? Expert groups advise to have lung cancer screenings at centers with the proper experience. These facilities should have specialists on staff. They can handle follow-up appointments, questions, and care.

• Is there any cost associated with the annual screening? Medicare and many private health insurance plans cover lung cancers screenings. It’s a good idea to ask your healthcare provider whether insurance will cover it before scheduling a test.

If your healthcare provider thinks you may have lung cancer, you will need certain exams and tests to be sure. Diagnosing lung cancer starts with your healthcare provider asking you questions. You'll be asked about your health history, your symptoms, possible risk factors, and family history of disease. A physical exam will be done. You might need to:

• Have a sputum cytology test . Each morning for 3 to 5 days in a row, you'll collect the mucus (sputum) that you cough up from your lungs. It's then sent to a lab and looked atunder a microscope to see if there are cancer cells in it.

• Have blood drawn. A needle might be used to take a small amount of blood from your hand or arm. Blood tests can show how well certain organs are working and give an idea of your overall health.

• Get a chest X-ray. This is done to look for changes in your lungs, like tumors or fluid buildup.

• Schedule other imaging tests. These are done to get a better picture of your lungs. A CT scan gives detailed X-ray pictures of the inside of your body and is most often used.

Any of these tests might suggest that you have lung cancer. If imaging tests show something that doesn't look normal, such as a mass or fluid, you'll need to have a biopsy. This is when a healthcare provider takes out a tiny sample of the mass or some of the fluid for testing at a lab. A biopsy is almost always needed to diagnose lung cancer.

The way a biopsy sample is taken out depends partly on where the tumor is and how big it is. Your healthcare provider may suggest one or more of the tests below to help do a biopsy and diagnose lung cancer.

After any kind of biopsy, the tissue samples are sent to a lab. They're looked at under a microscope and tested for cancer cells. It often takes up to a week for biopsy results to come back. Along with telling if you have lung cancer, a biopsy can often tell exactly what kind of lung cancer it is.

A lung biopsy can be done in many ways:

• Bronchoscopy

• Needle biopsy

• Thoracentesis

• Thoracotomy or thoracoscopy 

Each is briefly described below. Your healthcare provider can give you more details on the kind of biopsy you're going to have.

A pulmonologist often does this test. This healthcare provider specializes in lung diseases. The pulmonologist uses a long, thin, lighted tube called a bronchoscope to get a sample in this type of biopsy. The bronchoscope may be flexible or rigid. It's put in through your mouth or nose, through your breathing passages, and into your lungs. It has a tiny camera on the end so that your healthcare provider can see inside your lungs to get the sample from the right place.

This is also called needle aspiration or transthoracic needle aspiration. Your healthcare provider may use this test if the tumor can’t be reached with a bronchoscope. To do it, a thin, hollow needle is put through the skin of your chest and into the tumor to remove some tissue. Often an X-ray, ultrasound, or CT scan is done at the same time. This helps the healthcare provider see the tumor and guide the needle into it. 

This is also called a pleural fluid aspiration or a pleural tap. It might be done if fluid has built up around your lungs. It's used to see if the fluid contains cancer cells. A healthcare provider puts a thin, hollow needle through your skin to drain out the fluid. This test may be done to diagnose lung cancer. It's also used to drain fluid that's making it hard for you to breathe.

Thoracotomy and thoracoscopy are types of surgery done in an operating room. The surgeon opens up your chest to look for lung cancer. This is often done when the healthcare provider can’t make a clear diagnosis using any of the other methods. If possible, the surgeon takes out the entire tumor.    

Ask your healthcare provider how long it will take to get your test results and how you'll get them. Will it be a phone call? Do you need to set up an appointment?

If lung cancer is found, your provider will talk with you about other tests you may need. Make sure you understand the results and what your next steps should be.