Lung cancer risks, symptoms, and diagnosis

Lung cancer risks, symptoms, and diagnosis

Author
Karl W Thomas, MD
Section Editor
James R Jett, MD
Deputy Editor
Michael E Ross, MD

Disclosures

INTRODUCTION — 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. It is usually caused by cigarette smoke, but there are other factors that can increase the risk of lung cancer in the home and the workplace.

When a person develops lung cancer, tests are done to determine the type of lung cancer and the stage of the disease. This article will review the risks for developing lung cancer, the different types of lung cancer, signs and symptoms of lung cancer, and the medical testing required to confirm the diagnosis and determine the cancer’s size and location.

The treatment of lung cancer is discussed separately.

(See “Patient information: Non-small cell lung cancer treatment; stage I to III cancer”.)
(See “Patient information: Non-small cell lung cancer treatment; stage IV cancer”.)
(See “Patient information: Small cell lung cancer treatment”.)
More detailed information about lung cancer is available by subscription.

(See “Overview of the initial evaluation, treatment and prognosis of lung cancer”.)
(See “Overview of the treatment of advanced non-small cell lung cancer”.)
RISKS FOR LUNG CANCER

Smoking — Cigarette smoking is the biggest risk factor for lung cancer; it causes 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, are major risk factors for cancers of the mouth, throat, and lungs. The risk of lung cancer increases with the number of cigarettes smoked and the number of years of smoking.

The risk of cancer remains high for several years after quitting smoking but is lower than a smoker’s risk within 5 to 10 years after quitting. A former smoker’s risk of lung cancer is never as low as a nonsmoker’s risk.

Environmental factors — Exposure to substances at work or in the environment can increase a person’s risk of developing lung cancer. This includes secondhand tobacco smoke, asbestos, arsenic, radiation, and some chemicals. Dust and fumes from nickel, chromium, and other metals may also increase the risk of lung cancer.

An important risk factor for lung cancer in the home is radon. Radon is a radioactive gas that occurs naturally in the ground. Radon can leak out of the ground and then become trapped in houses or buildings, where it is then inhaled. You cannot see or smell radon, which is why testing for radon is often recommended (see www.epa.gov/radon/pubs/citguide.html).

Age and genetic risk factors — 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.

Some people have a genetic risk or predisposition for lung cancer. Anyone with a first-degree relative (parent, brother, sister) with lung cancer has a higher risk of developing lung cancer themselves.

LUNG CANCER SYMPTOMS — Most people with lung cancer have one or more symptoms. However, the symptoms of lung cancer are similar to the symptoms of many other more common and less serious 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. The cough can be a dry or may produce sputum (phlegm). (See “Patient information: Chronic cough in adults”.)
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.
INITIAL TESTING AND DIAGNOSIS — If you have symptoms that suggest lung cancer, your doctor or nurse will perform a complete exam and a chest X-ray.

If the chest X-ray shows a mass in your lung that could be a tumor, additional testing is performed. This may include blood work and a CT scan of the lower neck, entire chest, and upper part of the abdomen.

To confirm the diagnosis, you will need to have a piece of the tumor removed and examined (called a biopsy). A biopsy can be done in one of several ways:

Bronchoscopy is a procedure where a flexible tube with a camera is inserted through your mouth into the windpipe (called the trachea). This procedure is described in detail separately. (See “Patient information: Fiberoptic bronchoscopy”.)
CT-guided fine needle biopsy is performed by locating the tumor with a CT scan and using a thin needle through the skin, into the lung, to remove a tiny sample of tissue.
Needle aspiration is performed by inserting a needle into lumps that can be felt under the skin or into fluid collections in the chest.
Surgery may be needed if the tumor is small and it is not possible to get a sample of tissue any other way.
TYPES OF LUNG CANCER — There are many different kinds of lung cancer. However, there are two main categories:

Small cell lung cancer is found in about 10 to 15 percent of patients.
Non-small cell lung cancer (abbreviated NSCLC) includes 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 behave differently and are treated differently than non-small cell cancers. Small cell cancer tends to be more aggressive and can spread quickly.

STAGING NON-SMALL CELL LUNG CANCER — Once lung cancer is diagnosed, the next step is to determine its stage. Staging is a system used to describe the aggressiveness and spread of a cancer. A non-small cell lung cancer’s stage is based on:

The size and location of the tumor
Whether the tumor has invaded lymph nodes or tissues outside the lung but in the chest
Whether the tumor has spread to places distant from the chest (eg, brain, bones)
Non-small cell lung cancer stages range from I to IV:

Stage I — The tumor is smaller than 5 cm and has not spread outside the chest, to any of the other tissues in the chest, or to the lymph nodes (figure 1). (See “Patient information: Non-small cell lung cancer treatment; stage I to III cancer”.)
Stage II — Stage II means that the tumor is not larger than 7 cm but has spread to the lymph nodes, invaded the tissues surrounding the lung, or started to invade the large bronchial tubes (figure 2). The affected lymph nodes are only within the lung where the tumor is located. (See “Patient information: Non-small cell lung cancer treatment; stage I to III cancer”.)
Stage III — Stage III disease means that the tumor can be any size, but has spread to the lymph nodes in the center of the chest (called the mediastinum) or has spread to the rib cage, heart, swallowing tube (called the esophagus) or to the trachea (figure 3).
Stage IV — The cancer has caused fluid to collect around the lung or heart (called a malignant effusion), has spread to the opposite lung, or has spread to distant locations, like the brain, liver, or bones (figure 4). (See “Patient information: Non-small cell lung cancer treatment; stage IV cancer”.)
In general, lower-stage cancers are less aggressive and require different kinds of treatment than do higher-stage cancers. Stage I to III non-small cell lung cancers are referred to as localized cancers, while stage IV is called advanced cancer.

STAGING SMALL CELL LUNG CANCER — The system used to stage small cell lung cancer (SCLC) is different from that used for non-small cell lung cancer (NSCLC). This is because SCLC tends to have different growth patterns and a different prognosis. SCLC is categorized more simply 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.
Extensive disease — This refers to small cell lung cancers that have spread to both sides of the chest or have metastasized to distant locations outside the chest.
The treatment and prognosis of SCLC depends upon the classification. This is discussed in detail in a separate topic review. (See “Patient information: Small cell lung cancer treatment”.)

CLINICAL TRIALS — 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:

www.cancer.gov/clinicaltrials/learning/
file://clinicaltrials.gov/
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

 

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:

Patient information: Non-small cell lung cancer treatment; stage I to III cancer
Patient information: Non-small cell lung cancer treatment; stage IV cancer
Patient information: Small cell lung cancer treatment
Patient information: Chronic cough in adults
Patient information: Fiberoptic bronchoscopy

Professional Level Information:

Adjuvant systemic therapy in resectable non-small cell lung cancer
Cigarette smoking and other risk factors for lung cancer
First-line chemotherapy for small cell lung cancer
Initial systemic therapy for advanced non-small cell lung cancer without an epidermal growth factor receptor mutation or the ALK fusion oncogene
Investigational approaches for advanced non-small cell lung cancer
Management of stage I and stage II non-small cell lung cancer
Management of stage III non-small cell lung cancer
Molecular markers in non-small cell lung cancer
Multiple primary lung cancers
Overview of the initial evaluation, treatment and prognosis of lung cancer
Overview of the risk factors, pathology, and clinical manifestations of lung cancer
Pathobiology and staging of small cell carcinoma of the lung
Pathology of lung malignancies
Preoperative evaluation for lung resection
Role of imaging in the staging of non-small cell lung cancer
Screening for lung cancer
Small molecule epidermal growth factor receptor inhibitors for advanced non-small cell lung cancer
Treatment of refractory and relapsed small cell lung cancer
Women and lung cancer
Overview of the treatment of advanced non-small cell lung cancer

The following organizations also provide reliable health information.

National Cancer Institute
(www.cancer.gov/cancertopics/types/lung)

American Society of Clinical Oncology
(www.cancer.net/patient/Cancer+Types/Lung+Cancer)

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