An Overview of Lung Cancer - Symptoms, Risk Factors, Diagnosis

Lung cancer is a type of cancer that begins in the lungs. The lungs are two organs in the chest that take in oxygen when we inhale and release carbon dioxide when we exhale.
People who smoke have the greatest risk of lung cancer. The risk of lung cancer increases with the length of time and number of cigarettes smoked.

Symptoms. In its earliest stages, lung cancer typically doesn’t cause signs and symptoms. Signs and symptoms usually don’t occur until the disease has advanced and progressed.

Signs and symptoms of lung cancer may include:

A new cough that doesn’t go away
Changes in a chronic cough or “smoker’s cough”
Coughing up blood, even a small amount
Shortness of breath
Chest pain
Wheezing
Hoarseness
Losing weight without trying
Bone pain
Headache

Most often these symptoms are not due to cancer. Other health problems can cause some of these symptoms. Anyone with such symptoms should see a doctor to be diagnosed and treated as early as possible

Risk Factors Studies have found the following risk factors for lung cancer:

Tobacco smoke: Tobacco smoke causes most cases of lung cancer. It’s by far the most important risk factor for lung cancer. Harmful substances in smoke damage lung cells. That’s why smoking cigarettes, pipes, or cigars can cause lung cancer and why secondhand smoke can cause lung cancer in nonsmokers. The more a person is exposed to smoke, the greater the risk of lung cancer.
Radon: Radon is a radioactive gas that you cannot see, smell, or taste. It forms in soil and rocks. People who work in mines may be exposed to radon. In some parts of the country, radon is found in houses. Radon damages lung cells, and people exposed to radon are at increased risk of lung cancer. The risk of lung cancer from radon is even higher for smokers.
Asbestos and other substances: People who have certain jobs (such as those who work in the construction and chemical industries) have an increased risk of lung cancer. Exposure to asbestos, arsenic, chromium, nickel, soot, tar, and other substances can cause lung cancer. The risk is highest for those with years of exposure. The risk of lung cancer from these substances is even higher for smokers.
Air pollution: Air pollution may slightly increase the risk of lung cancer. The risk from air pollution is higher for smokers.
Family history of lung cancer: People with a father, mother, brother, or sister who had lung cancer may be at slightly increased risk of the disease, even if they don’t smoke.
Personal history of lung cancer: People who have had lung cancer are at increased risk of developing a second lung tumor.
Age over 65: Most people are older than 65 years when diagnosed with lung cancer.

Diagnosis. Tests for lung cancer include:

Physical exam: Your doctor checks for general signs of health, listens to your breathing, and checks for fluid in the lungs. Your doctor may feel for swollen lymph nodes and a swollen liver.
Chest x-ray: X-ray pictures of your chest may show tumors or abnormal fluid.
CT scan: Doctors often use CT scans to take pictures of tissue inside the chest. An x-ray machine linked to a computer takes several pictures. For a spiral CT scan, the CT scanner rotates around you as you lie on a table. The table passes through the center of the scanner. The pictures may show a tumor, abnormal fluid, or swollen lymph nodes.

Diagnosing Different Types of Lung Cancer. The only sure way to know if lung cancer is present is for a pathologist to check samples of cells or tissue. The pathologist studies the sample under a microscope and performs other tests. There are many ways to collect samples. Doctors order one or more of the following tests to collect samples:

Sputum cytology: Thick fluid (sputum) is coughed up from the lungs. The lab checks samples of sputum for cancer cells.
Thoracentesis: The doctor uses a long needle to remove fluid (pleural fluid) from the chest. The lab checks the fluid for cancer cells.
Bronchoscopy: The doctor inserts a thin, lighted tube (a bronchoscope) through the nose or mouth into the lung. This allows an exam of the lungs and the air passages that lead to them. The doctor may take a sample of cells with a needle, brush, or other tool. The doctor also may wash the area with water to collect cells in the water.
Fine-needle aspiration: The doctor uses a thin needle to remove tissue or fluid from the lung or lymph node. Sometimes the doctor uses a CT scan or other imaging method to guide the needle to a lung tumor or lymph node.
Thoracoscopy: The surgeon makes several small incisions in your chest and back. The surgeon looks at the lungs and nearby tissues with a thin, lighted tube. If an abnormal area is seen, a biopsy to check for cancer cells may be needed.
Thoracotomy: The surgeon opens the chest with a long incision. Lymph nodes and other tissue may be removed.
Mediastinoscopy: The surgeon makes an incision at the top of the breastbone. A thin, lighted tube is used to see inside the chest. The surgeon may take tissue and lymph node samples

Types of Lung Cancer

The pathologist checks the sputum, pleural fluid, tissue, or other samples for cancer cells. If cancer is found, the pathologist reports the type. The types of lung cancer are treated differently. The most common types are named for how the lung cancer cells look under a microscope:

Small cell lung cancer: About 13 percent of lung cancers are small cell lung cancers. This type tends to spread quickly
Non-small cell lung cancer: Most lung cancers (about 87 percent) are non-small cell lung cancers. This type spreads more slowly than small cell lung cancer.