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Patient education: Lung cancer risks, symptoms, and diagnosis (Beyond the Basics)

Karl W Thomas, MD
Section Editor
David E Midthun, MD
Deputy Editor
Sadhna R Vora, MD
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Lung cancer is a serious health problem that affects many people and their families. Lung cancer is the leading cause of cancer death in the United States. Cigarette smoke causes most lung cancers, but there are many other factors related to occupation, home, and family that increase the risk for lung cancer.

When a person develops lung cancer, tests are done to determine the type of lung cancer and if it has spread. When a cancer spreads, this is called metastasis. The size of the tumor and whether or not it is found in lymph nodes or other places in the body is described on a scale called the cancer stage. The stage is an important feature used to help choose the best treatments.

This article will first review the risks for developing lung cancer. The different types of lung cancer will also be reviewed. Next, this article will describe the signs and symptoms of lung cancer and the medical testing for patients who have lung cancer. Finally, this article will review the process of measuring the cancer’s size and locations to determine the stage.

The treatment of lung cancer is discussed separately.

(See "Patient education: Non-small cell lung cancer treatment; stage I to III cancer (Beyond the Basics)".)

(See "Patient education: Non-small cell lung cancer treatment; stage IV cancer (Beyond the Basics)".)

(See "Patient education: Small cell lung cancer treatment (Beyond the Basics)".)

More detailed information about lung cancer is available by subscription. (See 'Professional level information' below.)


An individual’s risk for getting lung cancer is dependent on many important factors: 1) how much tobacco they have smoked, 2) toxic exposures at home or work, 3) inherited predisposition to cancer, 4) the person’s age, and 5) health history of other cancers or lung disease. While many patients have more than one of these risk factors, there are some patients for whom the cause of cancer is unknown.

Smoking — Cigarette smoking is the most common risk factor for lung cancer. Smoking is estimated to cause 80 to 85 percent of all lung cancers in the United States. A smoker's risk of developing lung cancer is 10 to 30 times greater than that of a nonsmoker. All forms of tobacco and smoking, including pipes, cigars, and chewing tobacco, may cause cancers of the mouth, throat, and lungs.

The risk of lung cancer increases with the number of cigarettes smoked per day and the number of years of smoking. The quantity of cigarette smoking is summarized by the number of packs of cigarettes smoked per day multiplied by the number of years smoked. For example, a person who smoked one pack per day for 20 years would be said to have 20 pack-years of smoking exposure.

Quitting smoking can reduce the risk for lung cancer regardless of how many years a person has smoked. The risk of cancer remains high for several years after quitting smoking, but the risk does go down within 5 to 10 years after quitting. A former smoker's risk of lung cancer is never as low as a nonsmoker's risk.

Secondhand smoke — Secondhand smoke, sometimes called passive smoking or sidestream smoke, can be hazardous to adults and children. Secondhand smoke contains the same toxic substances as directly inhaled smoke. Secondhand smoke is an important cause of both lung cancer and heart disease deaths. Secondhand smoke is also a risk factor for respiratory problems such as bronchitis, sinus problems, and ear infections in both adults and children.

Radiation in the home — Radon in homes and workplaces is recognized as an important risk factor for lung cancer. Radon is a radioactive gas that occurs naturally in the ground. Radon leaks out of the ground and into houses or buildings where it is then inhaled. You cannot see or smell radon. This is why a special test of the air in the building is used to measure if radon is present. For more information about radon and testing recommendations, there are resources on the internet such as the United States Environmental Protection Agency (http://www.epa.gov/radon/), as well as many other state-based guides. Buildings that have elevated radon levels should have radon mitigation to vent the radon outside or to seal the building against radon entry.

Occupational and environmental factors — Substances at work or in the environment can increase a person's risk of developing lung cancer. Frequent indoor use of biomass fuels such as wood or coal for cooking is a risk factor for lung cancer, particularly for women. Industrial factors include work with asbestos, arsenic, radiation, and some chemicals. Dusts and fumes from nickel, chromium, and other metals used to create alloys in metal-working industries may also increase the risk of lung cancer.

Age and lung cancer — The risk of developing lung cancer increases with age. Lung cancer can occur in young people, although it is unusual in people younger than 40 years old. After age 40, the risk for developing lung cancer slowly increases every year.

Family and genetic risk — Some people have a genetic predisposition to lung cancer. Anyone with a first-degree relative (parent, brother, sister) with lung cancer has a slightly higher risk of developing lung cancer themselves.

Personal history of cancers or lung diseases — People who have had a prior cancer may also be at risk for developing lung cancer. This is particularly true for patients who have had another tobacco-related cancer such as throat cancer or those who have had radiation treatment in the area of their chest. In addition, patients who have chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis have an increased risk for developing lung cancer.


The most important steps to reduce the risks from lung cancer are to quit smoking, assess and mitigate radon in the home, and use appropriate protection in workplaces that have hazardous substances. For individuals who are between the ages of 55 and 74, have at least 30 pack-years of cigarette use, and continue to smoke, (or have quit within the past 15 years), screening with low-dose computed tomography may be recommended. (See "Patient education: Lung cancer prevention and screening (Beyond the Basics)".)


Most people with lung cancer have one or more symptoms. However, the symptoms of lung cancer may be the same as symptoms of other more common problems. If you are concerned about your symptoms, talk to your doctor or nurse.

The most common symptoms of lung cancer include:

Cough – Lung cancer can cause a new cough or a change in a chronic cough. (See "Patient education: Chronic cough in adults (Beyond the Basics)".)

Blood in sputum – This is called hemoptysis, and this requires medical evaluation if it occurs.

Shortness of breath

Wheezing, a whistling sound when you breathe

Chest pain can develop and may be dull, sharp, or stabbing

Voice hoarseness

Headache and swelling of the face, arms, or neck

Arm, shoulder, and neck pain can be caused by a tumor in the top of the lungs (called a Pancoast tumor). Other symptoms can include weakening of the hand muscles (due to pressure on the nerve that stimulates the arm), a droopy eyelid, and blurred vision.


If you have symptoms that suggest lung cancer, your doctor will perform an examination. If your findings are still concerning, more tests, including blood work and x-rays or scans will then be ordered.

If the chest x-ray or computed tomography (CT) scan shows an abnormality that could be a cancer, additional testing is performed to make a diagnosis. Usually, a small piece will need to be removed from the chest and examined with a microscope. This procedure is called a biopsy. Importantly, the decision to perform a biopsy does not mean that cancer is present. Biopsies are routinely performed to check for both cancer as well as many other diseases.

A biopsy can be done in one of several ways:

Bronchoscopy is a procedure where a flexible tube with a camera and other small instruments is inserted through your mouth or nose and then into the windpipe (called the trachea). This procedure is described in detail separately. (See "Patient education: Flexible bronchoscopy (Beyond the Basics)".)

Endobronchial ultrasound bronchoscopy or EBUS is a technique that combines flexible bronchoscopy with ultrasound to first see lymph nodes in the chest and then to take biopsies from enlarged lymph nodes.

CT-guided fine needle biopsy is performed by locating the tumor with a CT scan and inserting a thin needle through the skin to remove a tiny sample of tissue.

Needle aspiration is performed by inserting a needle into lumps or lymph nodes that can be felt under the skin or seen with an ultrasound.

Thoracentesis is insertion of a needle and small catheter into fluid collections in the chest to remove the fluid and look at it with a microscope.

Surgery may be needed to remove the tumor entirely if it is small or if other biopsy procedures have not been conclusive. The most common surgical procedures are mediastinoscopy, which is used to biopsy lymph nodes in the center of the chest; video-assisted thoracoscopic surgery (VATS), which is a less invasive way to biopsy lung tissue; and thoracotomy, which is a larger surgery to remove larger portions of lung tissue or tumors.


In addition to looking at the tumor with a microscope, some lung cancers may also be tested for abnormal proteins called biomarkers or for mutations in their DNA. If present, these biomarkers or genetic mutations may be used to determine the best treatment options. Common biomarkers in lung cancer include EGFR mutations, ALK translocations, and ROS1 translocations. This is a rapidly changing area of lung cancer research, and the list of biomarkers and targeted treatment options will continue to change.


There are many different kinds of lung cancer based on how they look under a microscope. However, there are two main categories used to determine the best treatment approach:

Small cell lung cancer is found in about 10 to 15 percent of patients.

Non-small cell lung cancer (often abbreviated NSCLC) includes most other types of lung cancer and is found in the remaining 85 to 90 percent of patients. There are subcategories of NSCLC, the most common of which are adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.

The reason that small cell cancer is separated from non-small cell cancers is that small cell cancers grow and metastasize differently. Small cell cancer tends to be more aggressive and can spread quickly. Small and non-small cancers have different treatment regimens for surgery, radiation, and chemotherapy.


Once lung cancer is diagnosed, the next step is to carefully measure the size of the tumor, determine its exact location, and look for evidence that it has spread. This process is called staging. Determining the stage of a lung cancer can be complicated because many different tests and procedures are used when determining the stage. The factors used to assign stage to non-small cell cancer are:

The size and location of the tumor. This is called the "T" factor.

Whether the tumor has invaded lymph nodes and tissues inside the chest. This is called the "N" factor.

Whether the tumor has spread to places outside the chest (for example, lung cancer can spread [metastasize] to places like the bones, liver, adrenal glands, or elsewhere). This is called the "M" factor.

T, N, and M factors are combined into groups that determine the overall cancer stage [1,2]. Non-small cell lung cancer stages range from I to IV. In general, the lower numbers (stages I and II) suggest that the tumor is smaller and has not spread out of the chest (figure 1 and figure 2). By comparison, the higher numbers (stage III and IV) suggest that the tumor is larger or has metastasized (figure 3 and figure 4 and figure 5).

In general, lower-stage cancers require different kinds of treatment than higher-stage cancers. Also, the overall health, goals, and preferences of the patient are very important in determining the best treatment approach. Early-stage lung cancers are generally managed with surgery to remove the tumor and surrounding lung. However, patients who cannot have surgery or who prefer not to have surgery may be treated with focused radiation therapy with or without chemotherapy. Stage III lung cancers are usually not treated with surgery, and the treatment options for patients with these tumors include chemotherapy and radiation therapy in combination. When the cancer has spread outside of the chest (stage IV), chemotherapy, targeted radiation therapy, and other treatments to minimize pain or anxiety may have a role in controlling the disease and its symptoms. Finally, participation in research studies of new cancer treatments may be considered by some patients, particularly those who have had testing for biomarkers and genetic mutations.

All patients should consider their healthcare goals and what quality of life means to them. Important goals for patients with advanced-stage cancer include treatments designed to control symptoms. Focusing on symptoms may improve quality of life, and often this approach can achieve a balance of acceptable survival times with treatment burdens.


Technical staging for small cell cancer is exactly the same as for non-small cell cancer. However, treatment options are usually determined by a simplified system. This is because small cell lung cancer has different growth patterns and a different prognosis. Small cell lung cancer is typically categorized as either "limited" or "extensive" disease. This system helps to determine which treatment will be most effective.

Limited disease – This refers to small cell lung cancers that are confined to one side of the chest and lymph nodes.

Extensive disease – This refers to small cell lung cancer that has spread to the opposite side of the chest or has metastasized (spread) to distant locations outside the chest.

The treatment and prognosis of small cell lung cancer (SCLC) depends upon whether disease is limited or extensive. This is discussed in detail in a separate topic review. (See "Patient education: Small cell lung cancer treatment (Beyond the Basics)".)


Progress in treating lung cancer requires better treatments. A clinical trial is a carefully controlled way to study the effectiveness of new treatments or new combinations of known therapies. Clinical trials are conducted around the world. Ask for more information about clinical trials, or read about clinical trials at:



Videos addressing common questions about clinical trials are available from the American Society of Clinical Oncology (http://www.cancer.net/pre-act).


Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Lung cancer (The Basics)
Patient education: Non-small cell lung cancer (The Basics)
Patient education: Small cell lung cancer (The Basics)
Patient education: Lung cancer screening (The Basics)
Patient education: Asbestos exposure (The Basics)
Patient education: Multiple pulmonary nodules (The Basics)
Patient education: Pulmonary nodule (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Non-small cell lung cancer treatment; stage I to III cancer (Beyond the Basics)
Patient education: Non-small cell lung cancer treatment; stage IV cancer (Beyond the Basics)
Patient education: Small cell lung cancer treatment (Beyond the Basics)
Patient education: Chronic cough in adults (Beyond the Basics)
Patient education: Flexible bronchoscopy (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Overview of the risk factors, pathology, and clinical manifestations of lung cancer
Cigarette smoking and other possible risk factors for lung cancer
Screening for lung cancer
Overview of the initial evaluation, treatment and prognosis of lung cancer
Pathology of lung malignancies
Pathobiology and staging of small cell carcinoma of the lung
Imaging of lung cancer
Preoperative evaluation for lung resection
Management of stage I and stage II non-small cell lung cancer
Management of stage III non-small cell lung cancer
Overview of the treatment of advanced non-small cell lung cancer
Personalized, genotype-directed therapy for advanced non-small cell lung cancer
Extensive stage small cell lung cancer: Initial management

The following organizations also provide reliable health information.

National Cancer Institute


American Society of Clinical Oncology



Literature review current through: Nov 2017. | This topic last updated: Mon Aug 21 00:00:00 GMT 2017.
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