Lung cancer is the top cause of cancer deaths in both men and women. But this wasn't always the case. Before the widespread use of mechanical cigarette rollers, lung cancer was rare. Today, smoking causes nearly 9 out of 10 lung cancer deaths, while radon gas, pollution, and other chemicals play a smaller role. Newly developed drugs can offer hope for people diagnosed today.
How Smoking Causes Lung Cancer
Cigarettes are not only packed with cancer-causing chemicals, but they also disarm the lungs' natural defense system. The airways are lined with tiny hairs known as cilia. These hairs protect the lungs by sweeping out toxins, bacteria, and viruses. Tobacco smoke stops the cilia from doing their job. This allows the cancer-causing chemicals to collect in the lungs.
Lung Cancer Symptoms
Lung cancer begins quietly. There are usually no symptoms or warning signs in the early stages. As it gets worse, symptoms may include:
A cough that won't go away
Chest pain, especially during deep breaths
Wheezing or shortness of breath
Coughing up bloody phlegm
Lung Cancer Screening
Can lung cancer be found early? A type of scan called spiral CT may pick up up early lung cancers in some people, but it's not clear whether it finds them early enough to save lives.
The U.S. Preventive Services Task Force recommends annual screening for lung cancer with low-dose CT in adults between 55 and 80 years who have a 30 "pack-year" smoking history and currently smoke or have quit within the past 15 years. Doctors figure out the pack year by multiplying the number of packs of cigarettes smoked every day by the number of years the person has smoked. Screening can stop once a person has not smoked for 15 years.
Diagnosing Lung Cancer
In most cases, doctors don't suspect lung cancer until it causes symptoms like a chronic cough or wheezing. At that point, your doctor will most likely order a chest X-ray or other imaging tests. You may also be asked to cough up phlegm for a sputum test. If either of these tests suggest cancer, you'll probably get a biopsy.
If a suspected tumor is visible on an X-ray, or cancer cells show up in a sputum test, a biopsy is used to confirm the diagnosis. A small sample of the suspicious mass is removed, usually with a needle, and doctors look at it under a microscope. By studying the sample, a doctor can learn whether the tumor is lung cancer, and if so, what kind.
Types of Lung Cancer
There are two main types of lung cancer. Small-cell lung cancer is more aggressive, meaning it can spread quickly to other parts of the body early in the disease. It is strongly tied to cigarette use and rarely seen in nonsmokers. Non-small-cell lung cancer grows more slowly and is more common. It's responsible for almost 85% of all lung cancers.
Lung Cancer Stages
Staging describes how far a patient's cancer has spread. There are different systems for the two main types of lung cancer. Small-cell lung cancer is divided into two stages: "Limited" means the cancer is confined to one lung and maybe nearby lymph nodes. "Extensive" means the cancer has spread to the other lung or beyond. Non-small-cell lung cancer is assigned a stage of 1 through 4, depending on how far it has spread.
Lung Cancer Survival Rates
The National Cancer Institute's latest statistics for lung cancer are for the years 2004 to 2010. Those statistics show the chances of living for 5 years after a lung cancer diagnosis varies from 4% to 54%, depending on the stage of disease. The 5-year survival rate continues to rise over time, research shows.
Treating Early-Stage Lung Cancer
When non-small-cell lung cancer is found before it spreads beyond one lung, surgery can sometimes help. The surgeon may remove the part of the lung that has the tumor, or if necessary, the entire lung. Some patients get radiation or chemotherapy after surgery to kill any remaining cancer cells. Surgery is usually not helpful to patients with small-cell lung cancer because it probably has already spread at the time of diagnosis.
Treating Advanced Lung Cancer
When lung cancer spreads too far to be cured, treatments can still help patients live longer and have a better quality of life. Radiation and chemotherapy can shrink tumors and help control symptoms, such as bone pain or blocked airways. Chemotherapy is usually the main treatment for small-cell lung cancer.
Targeted therapies are a newer form of cancer treatment that can be used together with chemotherapy or when other therapies don't work. One type prevents the growth of new blood vessels that feed cancer cells. It may help people with advanced lung cancer live longer. Other targeted therapies interrupt the signals that cause lung cancer cells to multiply, as shown in the image here.
Lung Cancer Clinical Trials
Clinical trials help doctors explore promising new treatments for lung cancer. And they help patients get comprehensive care. To see the current list of lung cancer clinical trials, visit the National Cancer Institute's site. And be sure to ask your doctor if there's a local clinical trial that might be right for you.
Life After Diagnosis
Being diagnosed with lung cancer can be a shock, and if it's linked to smoking, you may feel guilty as well. But don't waste time blaming yourself. Instead, experts suggest looking forward. It's never too late to make healthy changes to your lifestyle. There's evidence that patients who quit smoking after learning they have lung cancer do better than those who keep smoking.
Lung Cancer and Secondhand Smoke
While smoking is the top cause of lung cancer, it is not the only risk factor. Breathing in secondhand smoke at home or at work also appears to raise your risk. People who are married to smokers are 20% to 30% more likely to develop lung cancer than the spouses of nonsmokers.
Lung Cancer and Work Exposures
Some jobs can raise the risk of lung cancer in both smokers and nonsmokers. People who work with uranium, arsenic, and other chemicals should try to limit their exposure. Asbestos, which was once widely used in insulation, is a notorious cause of lung cancer. It is rarely used now, but workers who were exposed years ago are still at risk.
Lung Cancer and Radon Gas
Radon is a natural radioactive gas that occurs at higher than normal levels in certain parts of the U.S. The gas can build up inside homes and raise the risk of lung cancer, especially in people who smoke. It is the second leading cause of lung cancer in the U.S. About 12% of lung cancer deaths are linked to radon exposure. The gas can't be seen or smelled, but can be detected with simple test kits.
Lung Cancer and Air Pollution
While it causes far fewer cases than smoking, air pollution may raise the risk of lung cancer. Experts think that pollution from cars, factories, and power plants may affect the lungs like secondhand smoke does. Worldwide, air pollution may have caused about 223,000 lung cancer deaths.
Other Risk Factors for Lung Cancer
They may include:
A family history of lung cancer
Drinking water that's high in arsenic
Lung cancer does happen to people with no well-known risk factors -- including those who've never smoked. Researchers don't know the cause yet, but lung cancer in nonsmokers appears to affect more women than men. And one type, adenocarcinoma, is more common in nonsmokers than smokers.
Lung Cancer Prevention
Lung cancer may be one of the deadliest forms of cancer, but it's also one of the most preventable. In two words: Don't smoke. And if you do, get the help you need to quit. Within 10 years of quitting, the risk of lung cancer will drop 30% to 50%.
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.