Introduction
Lung cancer is a disease in which malignant (cancerous) cells form in the tissues of the lung. It is one of the most common cancers, accounting for about 13% of all new cancer diagnoses. There are two main types of lung cancer – small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).
The most common symptoms of lung cancer include coughing (especially if it gets worse or doesn’t go away), coughing up blood, shortness of breath, wheezing, chest pain, hoarseness, weight loss, bone pain, headache, and fatigue. However, sometimes this cancer does not cause any symptoms until it has spread to other areas.
The main causes and risk factors are smoking, secondhand smoke, radon gas, asbestos, air pollution, family history, and other carcinogens. The risk of lung cancer greatly increases with the length and amount of tobacco use.
Doctors diagnose this by using imaging tests such as x-rays, CT scans, MRIs, and PET scans. A medical professional examines the sample under a microscope to confirm the diagnosis through a biopsy. If doctors find cancer, they conduct additional tests to determine the stage, or the extent to which the cancer has spread.
Treatment options depend on the type and stage of the cancer, overall health, and patient preferences. Common treatments include surgery, chemotherapy, radiation therapy, targeted drug therapy, and immunotherapy. Despite advances in treatment, lung cancer has a high mortality rate. However, outcomes are better when detected and treated early.
Types of Lung Cancer
Lung cancer is generally divided into two main categories based on the appearance of cancer cells under the microscope:
Small Cell Lung Cancer
This type of cancer tends to grow and spread faster than non-small cell lung cancer. Smoking strongly links to it, and current or former smokers most often see it. Small cell lung cancer accounts for about 10-15% of lung cancers.
Non-Small Cell Lung Cancer
Non-small cell lung cancer is more common than small cell lung cancer and has three main subtypes:
- Adenocarcinoma – This is the most common type of lung cancer, accounting for 40% of cases. It develops from cells that line the alveoli of the lungs. The outer regions of the lungs typically contain it.
- Squamous cell carcinoma – This type accounts for 25-30% of lung cancers. It starts in early versions of squamous cells, which are flat cells that line the inside of the airways in the lungs. A history of smoking often links it, and it tends to be found in the central part of the lungs next to a bronchus.
- Large cell carcinoma – This type makes up about 10-15% of lung cancers and can appear in any part of the lung. It tends to grow and spread quickly.
Other Types
There are some rarer types of lung cancer, including pleomorphic carcinoma, carcinoid tumor, salivary gland carcinoma, and sarcoma.
Symptoms
Lung cancer symptoms can vary from person to person, but some of the most common include:
Cough:
One of the most common symptoms of this cancer is a persistent cough that gets worse over time. The cough may be dry and hacking or produce phlegm (sputum). It may occur with or without chest pain. As this cancer grows, tumors can block airways or cause swelling and irritation, leading to a chronic, nagging cough. A cough caused by this cancer usually won’t go away with common cough medications.
Chest pain:
Lung cancer can cause sharp or dull pain in the chest, back, or shoulders. This pain may result from enlarged lymph nodes or metastases to the chest wall, pleura (lining around the lungs), or ribs. It can also occur if a lung tumor grows to press on surrounding nerves or structures. Chest pain from this cancer tends to get worse over time.
Wheezing:
The airways of the lungs can become narrowed from lung tumors or swollen lymph nodes, resulting in wheezing, shortness of breath, or difficulty breathing. Wheezing or noisy breathing is more common with central tumors that block airways, compared to tumors growing on the outside of the lungs. Airway blockages from this cancer can occasionally lead to respiratory infections like pneumonia.
Fatigue:
Advanced lung cancer or metastases can cause extreme fatigue and weakness. Cancer cells use a lot of the body’s energy, while also releasing chemicals that change metabolism and disrupt sleep. Severe fatigue can significantly impair quality of life for this cancer’s patients. Fatigue tends to worsen as this cancer advances. Treatments like radiation and chemotherapy can further add to tiredness.
Other possible lung cancer symptoms include repeated respiratory infections like bronchitis or pneumonia, hoarseness, coughing up blood (hemoptysis), swollen lymph nodes, bone pain, headaches, and weight loss. Many symptoms of this cancer do not appear until it has advanced and spread. This highlights the importance of this cancer screening for high risk individuals. If caught early, lung cancer is more treatable.
Causes and Risk Factors
The most common cause of lung cancer is smoking. Cigarette smoking accounts for about 90% of lung cancer cases. The longer you smoke and the more cigarettes you smoke per day, the greater your risk of lung cancer becomes. Pipe, cigar, and secondhand smoke also increase lung cancer risk.
Smoking
Cigarette smoke contains over 7,000 chemicals, many of which are toxic and can damage cells in the lungs. Smoking introduces carcinogens into the lungs that can lead to genetic mutations and cause lung cancer cells to develop. The carcinogens in tobacco smoke also compromise the lungs’ defenses against infection.
Radon Gas
Soil and rocks naturally release a radioactive gas known as radon. It cannot be seen, smelled, or tasted. Radon can accumulate in buildings and increase this cancer risk. The EPA estimates that radon causes about 21,000 lung cancer deaths per year in the U.S. Testing kits can detect radon in your home. Steps can then be taken to reduce radon levels if necessary.
Asbestos
Asbestos refers to a group of minerals that occur naturally as fiber bundles. Many building, insulation, and fireproofing materials have used asbestos due to its durability and heat resistance. Inhaling asbestos fibers can lodge in lung tissue, causing lung damage and cancer. Asbestos exposure is now highly regulated.
Diagnosis
Lung cancer is typically diagnosed through a combination of imaging tests and biopsies. Common imaging tests used to detect lung tumors include:
Chest X-ray:
This is often the first test used if lung cancer is suspected based on symptoms. It can reveal suspicious areas in the lungs but cannot definitively diagnose cancer.
CT scan:
A computed tomography (CT) scan takes cross-sectional X-rays to create detailed 3D images of organs and tissues inside the body. CT scans of the chest are considered the best imaging test for detecting lung tumors, determining their exact location, and seeing if they have spread.
PET scan:
A positron emission tomography (PET) scan involves injecting a radioactive tracer into the bloodstream that accumulates in cancer cells. When paired with a CT scan (PET-CT scan), it provides a view of where cancer is metabolically active in the body. This helps determine if lymph nodes are affected or if the cancer has spread.
MRI scan:
Magnetic resonance imaging (MRI) may be done to better visualize the tumor, particularly for lung cancer near the top of the lungs or spine.
The only definitive way to diagnose lung cancer is by obtaining cells or tissue from the suspicious area for examination under a microscope. The main procedures used are:
- Sputum cytology: Looking at sputum (mucus coughed up from the lungs) under a microscope for cancer cells. This is best for diagnosing cancers that start centrally in larger airways of the lung.
- Needle biopsy: Using CT scan guidance, a special hollow needle is passed through the chest wall to extract a sample of cells from the tumor to examine. Several samples may need to be collected to confirm a diagnosis.
- Bronchoscopy: A bronchoscope (thin, flexible tube with light and camera on the end) is passed through the nose or mouth and into the airways. It allows doctors to visually examine the airways and to take samples of tissue or lung fluids.
- Mediastinoscopy: A small incision is made at the top of the breastbone to insert a thin tube with a camera (mediastinoscope). This lets the doctor see lymph nodes and take samples from the region between the lungs to check for cancer spread.
- Thoracoscopy: A thoracoscope (thin tube with a camera) is inserted through small incisions in the chest wall, allowing examination of the lungs and chest cavity. Tissue samples can also be collected during this procedure.
Accurately identifying and diagnosing lung cancer is key for determining the best treatment approach. Various imaging tests and tissue biopsies help oncologists confirm the presence and location of lung tumors. Ongoing screening may be recommended after treatment to monitor for recurrence.
Staging
Lung cancer staging is based on the size of the tumor, whether it has spread to nearby lymph nodes, and whether it has metastasized to other parts of the body. Determining the stage of this cancer helps doctors develop the best treatment plan.
The TNM system is used for staging this cancer:
- T describes the size and location of the main tumor
- N describes whether cancer has spread to nearby lymph nodes
- M indicates whether cancer has metastasized to other parts of the body
Stage I
The cancer is located only in the lungs and has not spread to any lymph nodes. Stage 1A tumors are smaller than 2 cm across, while 1B tumors are 2-3 cm across. This is the earliest stage.
Stage II
The tumor is larger than 3 cm but smaller than 5 cm across and/or it has spread to nearby lymph nodes but not distant sites. Stage IIA involves lymph node spread on the same side as the tumor, while IIB involves lymph node spread on the opposite side.
Stage III
The tumor is larger than 5 cm across or any size with spread to lymph nodes above the collarbone or near the heart. Stage IIIA has spread to lymph nodes only on the same side, IIIB has spread to lymph nodes on the opposite side or above the collarbone, and IIIC has spread to lymph nodes on both sides or above the collarbone.
Stage IV
The cancer has metastasized and spread to distant lymph nodes or organs such as the liver, bones, or brain. This is the most advanced stage.
Determining the stage of this cancer allows doctors to choose the most appropriate treatments and predict prognosis. Catching lung cancer early in Stage I or II leads to better chances for survival.
Treatment
Treatment options for lung cancer depend on the type of lung cancer, the stage, whether the cancer has spread and other factors. These options may include:
Surgery
Operations used to treat lung cancer include:
- Wedge resection to remove a small section of lung that contains the tumor along with a margin of healthy tissue.
- Segmentectomy to remove a larger portion of lung, but not an entire lobe.
- Lobectomy to remove the entire lobe of one lung.
- Pneumonectomy to remove an entire lung.
Surgery may be used for early stage non-small cell lung cancer when the cancer is confined to the lungs. Surgery may also be used to remove this cancer that has spread to the brain or adrenal glands.
Chemotherapy
Chemotherapy uses drugs to kill cancer cells. It can be given as pills you take by mouth or by intravenous injection. For lung cancer, chemotherapy is most often given after surgery to kill any remaining cancer cells. Chemotherapy may also be used as the main treatment along with radiation therapy for cancers that can’t be removed surgically.
Radiation Therapy
This treatment uses high-energy beams to kill cancer cells. Radiation may be used before or after surgery. It may also be given as the main treatment in combination with chemotherapy for this cancer that cannot be surgically removed.
Radiation therapy is carefully targeted to spare healthy tissue. New techniques allow doctors to focus radiation more precisely on the cancer.
Targeted Drug Therapy
For cancers with specific genetic mutations, targeted drugs can block signals that tell cancer cells to grow and divide. These precision medicines target foundational mutations in cells. Examples for lung cancer include drugs that target mutations in the EGFR, ALK and ROS1 genes. Testing helps match each patient with the most effective targeted drug.
Outlook and Survival Rates
The 5-year survival rate for people with lung cancer varies significantly depending on the stage at which the cancer is diagnosed. When detected at an early, localized stage, the 5-year survival rate is around 60%. However, only 16% of lung cancers are diagnosed at this early stage.
For lung cancers that have spread regionally to nearby lymph nodes or surrounding tissue, the 5-year survival rate drops to around 30%. Once the cancer has metastasized and spread to more distant parts of the body, the 5-year survival rate is only 5%.
Overall, the 5-year survival rate for this cancer is around 18%, because most patients are diagnosed after the cancer has already started spreading. However, survival rates can vary considerably based on the specific type and subtype of lung cancer. For example, small cell lung cancer typically has lower survival rates than non-small cell lung cancer.
The outlook is better when this cancer is caught early. That’s why it’s important for people at high risk to get regular lung cancer screenings, even if they don’t have any symptoms yet. Quitting smoking, eating well, staying active, and getting regular health checkups are other ways to improve your chances. With treatment advances improving, more people are living longer with lung cancer. Support groups and resources can help you stay positive.
Prevention
The best way to prevent lung cancer is to avoid risk factors whenever possible. The most important thing you can do to lower your risk of this cancer is to avoid tobacco smoke.
Don’t smoke
If you don’t smoke, don’t start. Talk to your children about not smoking so that they can understand how to avoid this major risk factor for this cancer. Begin conversations about tobacco use with your kids when they’re 6 or 7 years old and continue through their teen years. Stopping even after decades of use can significantly reduce your risk of this cancer.
Quit smoking
Quitting at any age can lower your risk of lung cancer. Quitting smoking before age 40 reduces your risk of dying from lung cancer by about 90%, and quitting by age 50 cuts your risk in half. No matter what your age or how long you’ve smoked, quitting can help you live longer. Ask your doctor about stop-smoking aids and support groups.
Avoid secondhand smoke
Don’t allow other people to smoke indoors and insist that smokers step outside. You also should avoid public places that permit smoking. Exposure to passive smoke at home or work increases this cancer risk by 20% to 30%.
Test your home for radon
This radioactive gas is the second-leading cause of lung cancer in the U.S. Radon seeps into homes from soil and rocks beneath foundations. Radon levels are usually highest in basements and ground floors. Have a radon test kit installed in your home to check radon levels. Make repairs if levels are high.
Making lifestyle changes and understanding your risk of this cancer are the best ways to protect yourself and your loved ones. Avoid tobacco in all forms, test your home, and get lung cancer screening if you’re at high risk. Taking these preventive measures offers you the best defense against this cancer.
Support and Resources
Receiving a lung cancer diagnosis can feel overwhelming, but many resources are available to help patients and caregivers throughout treatment and recovery. Support groups provide a caring community to share experiences and helpful advice. Financial assistance options can ease the financial burden of medical expenses.
Support Groups
- The American Lung Association’s [Lung Cancer Survivorship Support](https://www.lung.org/lung-health-diseases/lung-disease-lookup/lung-cancer/living-with-lung-cancer/emotional-social-support) community connects patients and caregivers with others affected by lung cancer through in-person meetups and online discussion groups.
- [LUNGevity Foundation](https://lungevity.org/for-patients-caregivers/lung-cancer-support-resources) offers a Survivor Match Program to pair lung cancer patients with volunteer peer mentors who have gone through similar experiences.
- [Cancer Support Community](https://www.cancersupportcommunity.org/lung-cancer) provides support groups, education workshops, and healthy lifestyle programs at locations across the U.S.
Financial Assistance
– Several organizations offer financial aid and copay assistance to help patients afford medical treatment. These include the [HealthWell Foundation](https://www.healthwellfoundation.org/), [CancerCare](https://www.cancercare.org/), [Patient Advocate Foundation](https://www.patientadvocate.org/), and drug manufacturers’ assistance programs.
