Lung Cancer Guide

Anatomy of the Lungs

The lungs are a fundamental paired organ in the human body that help us breathe. Let’s look at some basics of lung anatomy:

1. Number and Location: Humans have two lungs, located in the chest cavity, one on the left and one on the right of the heart. The left lung is slightly smaller to accommodate the heart.
2. Lobes: The right lung has three lobes or sections, called the upper, middle, and lower lobes, while the left lung has two lobes – the upper and lower lobes.
3. Bronchi: The main airway that carries air from the throat to the lungs is called the trachea. The trachea divides into two smaller airways called bronchi, each leading to one lung. The bronchi continue to divide into smaller and smaller branches called bronchioles.
4. Alveoli: At the ends of the smallest bronchioles are tiny sacs called alveoli. This is where oxygen from the air we breathe enters the blood and carbon dioxide, which needs to be exhaled, leaves the blood.
5. Pleura: Each lung is covered by a thin membrane called the pleura. It helps the lungs move smoothly during breathing.

The lungs are extremely important because the oxygen they bring into the human body is needed by all cells to function and keep the body alive and healthy.

About Lung Cancer

Lung cancer usually begins in the cells that line the bronchi and parts of the lung such as the bronchioles or alveoli. Lung cancer is a serious malignant disease characterized by the development of tumors in the tissues of the lungs. It is one of the most common types of cancer and a leading cause of cancer death globally.

Types of Lung Cancer

There are two main types of lung cancer:

1. Non-Small Cell Lung Cancer (NSCLC): This is the most common type of lung cancer, accounting for about 80-90% of cases. There are subtypes of non-small cell lung cancer. The most common are:

• Adenocarcinoma: Begins in mucus-producing cells and makes up about 40% of lung cancers. Although this type of lung cancer is most often diagnosed in current or former smokers, it is also the most common lung cancer in non-smokers.
• Squamous Cell Carcinoma: Usually develops in the larger airways of the lung.
• Large Cell Undifferentiated Carcinoma: Can appear in any part of the lung and does not clearly look like squamous cell carcinoma or adenocarcinoma.

1. Small Cell Lung Cancer (SCLC): Usually starts in the middle of the lungs and spreads faster than non-small cell lung cancer. It accounts for about 15% of lung cancers.

Symptoms of Lung Cancer

Symptoms of lung cancer may include:

• Shortness of breath
• Changes in the voice, such as hoarseness
• Chest pain
• Coughing or coughing up blood
• Persistent cough that does not go away
• Chest infection lasting more than three weeks or recurring
• Enlarged fingertips
• Loss of appetite
• Unexplained weight loss
• Fatigue

Screening for Lung Cancer

Three screening tests have been studied to see if they reduce the risk of dying from lung cancer:

1. Low-Dose Computed Tomography (LDCT): A procedure that uses low doses of radiation to make a series of very detailed pictures of areas inside the body using an x-ray machine that scans the body in a spiral path. This procedure is also called spiral CT.
2. Chest X-ray: An x-ray picture of the organs and bones inside the chest. X-rays are a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
3. Sputum Cytology: Sputum cytology is a procedure in which a sample of mucus that is coughed up from the lungs is looked at under a microscope to check for cancer cells.

Risk Factors for Developing Lung Cancer

• Smoking: Smoking is the most significant cause of lung cancer. There are other risk factors that can increase the risk of developing lung cancer.
• Other Substances: Some other substances also increase the risk of lung cancer. These include asbestos, silica, and diesel exhaust. People can be exposed to them through their work or general life.
• Air Pollution: We know that air pollution can cause lung cancer. The risk depends on the levels of air pollution you are regularly exposed to.
• Previous Lung Disease: Previous lung diseases can increase the risk of lung cancer. These diseases may include:
• Chronic Obstructive Pulmonary Disease (COPD): Long-term lung diseases like emphysema and chronic bronchitis. COPD usually develops due to long-term damage to the lungs from inhaling harmful substances, usually cigarette smoke. Your risk of lung cancer is higher if you have COPD or a lung infection compared to people who do not have it.
• Idiopathic Pulmonary Fibrosis: This also increases the risk of developing lung cancer.
• Family History of Lung Cancer: Your risk of lung cancer is higher if you have a close relative - a parent or sibling who has had lung cancer.
• High Doses of Beta-Carotene: Some studies suggest that taking high doses of beta-carotene around 20 to 30 milligrams a day from supplements may increase the risk of lung cancer in people who smoke.

Diagnosing Lung Cancer

Several tests can be done to determine the diagnosis of lung cancer:

Chest X-ray: The x-ray can show larger tumors that are more than 1 cm wide.

Computed Tomography (CT) Scan: CT uses x-rays to make detailed pictures inside your body and create a cross-sectional image. CT scans can detect smaller tumors as well as provide information about the tumor and lymph nodes.

Doctors may use a CT scan to:

• Diagnose and stage lung cancer
• Check if the cancer has spread to the liver, adrenal glands, lower part of the neck, or lymph nodes in the chest

PET Scan: PET-CT scanning combines CT and PET scanning. PET stands for positron emission tomography. PET scanning uses a mildly radioactive drug to show areas of your body where cells are more active than normal.

CT scanning takes a series of x-rays of your entire body and assembles them to create a three-dimensional (3D) image. PET-CT scanning can help show:

• Exactly where the cancer is in the lung
• If it has spread elsewhere in the body and to the lymph nodes in the chest
• How aggressive (metabolically active) the cancer is
• The best treatment for your cancer
• If your cancer has returned
• How well the cancer treatment is working
• The need for radiotherapy treatment

Lung Function Test: You may have a lung function test known as spirometry, which checks how well your lungs are working.

Biopsy: During a biopsy, a doctor or nurse takes samples of cells or tissues from the affected area. They examine the biopsy samples under a microscope to check for cancer cells. A biopsy is usually done to confirm if you have lung cancer. There are different ways to collect biopsies, including:

• Bronchoscopy with Transbronchial Biopsy: Bronchoscopy is a test to look inside the airways (breathing tubes) in the lungs.
• CT and Biopsy
• Lung Needle Biopsy: This test is called percutaneous lung biopsy. Your doctor takes a sample of lung tissue by passing a needle into the lung.
• EBUS - Endobronchial Ultrasound and Biopsy: Endobronchial ultrasound for lung cancer is also called endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA). This test uses a narrow, flexible tube to look inside the airways in the lungs. The tube has an ultrasound probe. This method uses high-frequency sound waves to create pictures of the lungs and structures outside the walls of the airways, such as lymph nodes.
• EUS - Endoscopic Ultrasound and Biopsy: This test combines ultrasound and endoscopy to examine the areas around your esophagus.
• Neck Lymph Node Biopsy: You may have this test if your doctor has seen changes in the lymph nodes in your neck on a CT scan. This can determine if there are cancer cells in the lymph nodes.

If tests show you have lung cancer, your specialist will order additional tests. These may help in staging lung cancer. Then, the following tests may be needed:

• Mediastinoscopy: Sometimes, mediastinoscopy is done instead of EBUS or EUS. This allows the doctor to examine the area in the middle of the chest and nearby lymph nodes.
• Thoracoscopy: Thoracoscopy allows the doctor to look at the lining of the lungs. It is usually performed under general anesthesia.
• Magnetic Resonance Imaging (MRI): MRI scanning uses magnetism to build a detailed picture of areas in the body.

Genetic Mutation Testing in Lung Cancer

Some types of lung cancer, such as non-small cell lung cancer, have changes in certain genes and proteins. These changes can be used as targets for specific drug treatments.

Genes are found in the chromosomes in all cells. They tell the cell which proteins to make. Scientists can examine lung cancer samples in a laboratory and look for genetic changes (mutations) that alter how the cancer grows.

Some non-small cell lung cancers have changes in genes that cause cancer to grow and divide, such as:

• Epidermal Growth Factor Receptor (EGFR) gene
• Anaplastic Lymphoma Kinase (ALK) gene
• ROS1 gene
• BRAF gene
• Neurotrophic Tyrosine Receptor Kinase (NTRK) gene
• Mesenchymal-Epithelial Transition (MET) gene
• RET gene
• KRAS gene

Non-small cell lung cancer cells may also have higher than normal amounts of PD-L1 proteins. PD-L1 proteins are also found in normal cells. Your doctor may test for changes in one or more of these genes before starting treatment.

To have these tests, your cancer must be non-small cell lung cancer that has spread to the area around the lung or elsewhere in the body (advanced stage cancer).

After Diagnosis

If it is confirmed that you have lung cancer, you may feel shocked, upset, anxious, or confused. These are normal reactions. Talk about your treatment options with your doctor, family, and friends. Seek as much information as you need. On the Health Navigator pages, you will find many more resources on lung cancer as well as other types of cancer.

Stages of Lung Cancer

Doctors use the same staging system for non-small cell lung cancer and small cell lung cancer. Your doctor can tell you the stage of your lung cancer using a system that assigns numbers from 1 to 4.

Stage 1 Lung Cancer: When the cancer is no larger than 4 cm and has not spread outside the lung or to lymph nodes, it is in the first stage. Stage 1 lung cancer is called early lung cancer or localized lung cancer.

Stage 2 Lung Cancer: The cancer can be of different sizes. It may have spread to nearby lymph nodes, other parts of the lung, or areas just outside the lung.

Stage 3 Lung Cancer: The cancer can be of any size and usually has spread to lymph nodes. It may also invade:

• Other parts of the lung
• Airways
• Surrounding areas outside the lung

The cancer may also have spread to tissues and structures farther from the lung but has not spread to other parts of the body.

Stage 2 and 3 lung cancer is called locally advanced lung cancer.

Stage 4 Lung Cancer: The cancer can be of any size. It may have spread to lymph nodes and one or more of the following:

• The cancer has spread to the lung on the other side.
• There are cancer cells in fluid in the pleura or around the heart.
• The cancer has spread to another part of the body – such as the liver, bones, or brain.

Stage 4 lung cancer is called metastatic or secondary lung cancer.

Staging of Small Cell Lung Cancer (SCLC)

Doctors can also divide small cell lung cancer (SCLC) into two stages:

• Limited Stage: Cancer cells can be seen in one lung and nearby lymph nodes.
• Extensive Stage: The cancer has spread outside the lung to the chest area or other parts of the body.

Treatment of Lung Cancer

Lung cancer treatment can include surgery, radiotherapy, chemotherapy, targeted therapy, immunotherapy drugs, or a combination of these. Follow the links to learn more about the application of each method.

Your treatment plan will depend on the stage and type of lung cancer and your overall health. A team of specialists should meet to discuss the best possible treatment for you. This team is called a multidisciplinary team and should include:

• Respiratory physician
• Specialist surgeon
• Cancer specialists (oncologists) who specialize in cancer treatment with cancer drugs (medical oncologist) and radiotherapy (clinical oncologist)
• Pathologist
• Pharmacist
• Radiologist
• Dietitian

Treatment Options for Small Cell Lung Cancer (SCLC)

The multidisciplinary team decides what treatment you need and may recommend a combination of treatment methods for maximum effectiveness. Possible treatment methods for small cell lung cancer are:

• Chemotherapy
• Radiotherapy
• Surgery
• Chemotherapy with radiotherapy (chemoradiotherapy)
• Radiotherapy to the brain (prophylactic cranial irradiation – also called PCI)
• Chemotherapy with or without immunotherapy

Treatment Options for Non-Small Cell Lung Cancer (NSCLC)

The multidisciplinary team decides what treatment you need and may recommend a combination of treatment methods for maximum effectiveness. Possible treatment methods for non-small cell lung cancer are:

• Surgery
• Radiotherapy
• Chemotherapy
• Chemotherapy with radiotherapy (chemoradiotherapy)
• Immunotherapy
• Targeted cancer drugs

For more information on lung cancer treatment, visit this page.