Types of Cancer : Lung Cancer

Definition

Lung cancer is the leading cause of cancer deaths in the United States, among both men and women. It claims more lives each year than colon, prostate, lymph and breast cancers combined.

Yet most lung cancer deaths could be prevented. That's because smoking accounts for nearly 90 percent of lung cancer cases. Your risk of lung cancer increases with the length of time and number of cigarettes you smoke. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer. Protecting yourself from other risk factors for lung cancer, such as exposure to asbestos, radon and secondhand smoke, also decreases your risk.

Symptoms

Lung cancer typically doesn't cause signs and symptoms in its earliest stages. Signs and symptoms of lung cancer typically occur only when the disease is advanced. 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

Causes

Lung cancer most commonly begins in the cells that line your lungs. Smoking causes the majority of lung cancers — both in smokers and in people exposed to secondhand smoke. But lung cancer also occurs in people who never smoked. In these cases, there may be no clear cause of lung cancer. Doctors have identified factors that may increase the risk.

How smoking causes lung cancer
Doctors believe smoking causes lung cancer by damaging the cells that line the lungs. When you inhale cigarette smoke, which is full of cancer-causing substances (carcinogens), changes in the lung tissue begin almost immediately. At first your body may be able to repair this damage. But with each repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.

Your lungs are full of blood vessels and lymph vessels, giving lung cancer cells easy access to travel to other parts of your body. For this reason, lung cancer may spread to other parts of your body before you experience any signs or symptoms. In many cases, lung cancer may spread before it can even be detected in the lungs.

Types of lung cancer
Doctors divide lung cancer into two major types based on the appearance of lung cancer cells under the microscope. Your doctor makes treatment decisions based on which major type of lung cancer you have. The two general types of lung cancer include:

• Small cell lung cancer. Small cell lung cancer, sometimes called oat cell carcinoma, occurs almost exclusively in heavy smokers and is less common than non-small cell lung cancer.
• Non-small cell lung cancer. Non-small cell lung cancer is an umbrella term for several types of lung cancers that behave in a similar way. Non-small cell lung cancers include squamous cell carcinoma, adenocarcinoma and large cell carcinoma.

Risk factors

A number of factors may increase your risk of lung cancer. Some risk factors can be controlled, for instance, by quitting smoking. And other factors can't be controlled, such as your sex. Risk factors for lung cancer include:

• Smoking. Smoking remains the greatest risk factor for lung cancer. Your risk of lung cancer increases with the number of cigarettes you smoke each day and the number of years you have smoked. Quitting at any age can significantly lower your risk of developing lung cancer.
• Your sex. Current or former women smokers have a greater risk of lung cancer than do men who have smoked an equal amount. Though it isn't known why, some experts speculate that women have a greater susceptibility to the cancer-causing substances found in tobacco. Others believe that estrogen may play a role. Women also are known to inhale more than men do, and they are less likely to quit.
• Exposure to secondhand smoke. Even if you don't smoke, your risk of lung cancer increases if you're exposed to secondhand smoke.
• Exposure to radon gas. Radon is produced by the natural breakdown of uranium in soil, rock and water that eventually becomes part of the air you breathe. Although unsafe levels of radon can accumulate in any building, the greatest exposure risk most people face is at home. Radon testing can determine whether levels are safe.
• Exposure to asbestos and other chemicals. Workplace exposure to asbestos and other substances known to cause cancer — such as arsenic, chromium, nickel and tar soot — also can increase your risk of developing lung cancer, especially if you're a smoker.
• Family history of lung cancer. People with a parent, sibling or other first-degree relative with lung cancer have an increased risk of the disease.
• Excessive alcohol use. Drinking more than a moderate amount of alcohol — no more than one drink a day for women or two drinks a day for men — may increase your risk of lung cancer.

Tests and diagnosis

Screening
Doctors aren't sure whether you should undergo screening for lung cancer. Even if you have an increased risk of lung cancer — for instance, if you're a smoker — it isn't clear that a chest X-ray or computerized tomography (CT) scan can be beneficial. Some studies show that these tests can find cancer earlier, when it may be treated more successfully. But other studies find that these tests often reveal more benign conditions that require invasive testing and expose people to unnecessary risks.

Screening for lung cancer is controversial among doctors. Studies are ongoing to determine what types of tests may be helpful and who would benefit from lung cancer screening. In the mean time, talk with your doctor if you're concerned about your risk of lung cancer. Together you can determine strategies to reduce your risk and decide whether screening tests are appropriate for you.

Diagnosis
If there's reason to think that you may have lung cancer, your doctor can order a number of tests to look for cancerous cells and to rule out other conditions. In order to diagnose lung cancer, your doctor may recommend:

• Imaging tests. An X-ray image of your lungs may reveal an abnormal mass or nodule. A CT scan can reveal small lesions in your lungs.
• Sputum cytology. If you have a cough and are producing sputum, looking at the sputum under the microscope can sometimes reveal the presence of lung cancer cells. Before the test, you may be asked to breathe a mildly irritating mist to help you produce more sputum.
• Tissue samples (biopsy). A sample of abnormal cells may be removed in a procedure called a biopsy in order to diagnose lung cancer. Your doctor can perform a biopsy in a number of ways, including bronchoscopy, in which your doctor examines abnormal areas of your lungs using a lighted tube that is passed down your throat and into your lungs; mediastinoscopy, in which an incision is made at the base of your neck and surgical tools are inserted behind your breastbone to take tissue samples; and needle biopsy, in which your doctor uses X-ray or CT images to guide a needle through your chest and into a suspicious lump or nodule to collect cells. A biopsy sample may also be taken from lymph nodes or other areas where cancer has spread, such as your liver.

Staging
Once your lung cancer has been diagnosed, your doctor will work to determine the extent, or stage, of your cancer. Your cancer's stage helps your doctor decide what treatment is most appropriate. Staging tests may include imaging procedures that allow your doctor to look for signs that cancer has spread beyond your lungs, such as magnetic resonance imaging (MRI), positron emission testing (PET) and bone scans. Not every test is appropriate for every person, so talk with your doctor about which procedures are appropriate for you.

Stages of non-small cell lung cancer

• Stage I. Cancer at this stage has invaded the underlying lung tissue but hasn't spread to the lymph nodes.
• Stage II. This stage cancer has spread to neighboring lymph nodes or invaded the chest wall.
• Stage IIIA. At this stage, cancer has spread from the lung to lymph nodes in the center of the chest.
• Stage IIIB. The cancer has spread locally to areas such as the heart, blood vessels, trachea and esophagus — all within the chest — or to lymph nodes in the area of the collarbone or to the tissue that surrounds the lungs within the rib cage (pleura).
• Stage IV. The cancer has spread to other parts of the body, such as the liver, bones or brain.

Stages of small cell lung cancer

• Limited. Cancer is confined to one lung and to its neighboring lymph nodes.
• Extensive. Cancer has spread beyond one lung and nearby lymph nodes, and may have invaded both lungs, more remote lymph nodes or other organs.

Complications

Lung cancer can cause complications, such as:

• Fluid in the chest (pleural effusion). Lung cancer can cause fluid to accumulate in the space that surrounds the lungs in the chest cavity (pleural space). Pleural effusion can result from cancer spreading outside the lungs or in reaction to lung cancer inside the lungs. Fluid accumulating in the chest can cause shortness of breath. Treatments are available to drain the fluid from your chest and reduce the risk that pleural effusion will occur again. Cancer that spreads to the pleura is considered inoperable, so surgery isn't an option for treatment.
• Cancer that spreads to other parts of the body (metastasis). Lung cancer often spreads (metastasizes) to other parts of the body — most commonly the opposite lung, brain, bones, liver and adrenal glands. Cancer that spreads can cause signs and symptoms, including pain, nausea, headaches or others based on what organ is affected. In some cases, treatments are available for isolated metastasis, but in most cases, the goal of treatment for metastasis is only to relieve signs and symptoms.
• Death. Unfortunately, survival rates haven't improved for people diagnosed with lung cancer. In most cases, the disease is fatal. Almost 60 percent, or three out of every five people, diagnosed with lung cancer die within a year. Keep in mind, however, that this number includes people diagnosed with all types of lung cancer at all stages of the disease. People diagnosed at the earliest stages have the greatest chances for a cure. Your doctor can discuss more relevant statistics about your chances for survival with you.

Treatments and drugs

You and your doctor choose a cancer treatment regimen based on a number of factors, such as your overall health, the type and stage of your cancer, and your own preferences. Treatment options typically include one or more treatments, including surgery, chemotherapy, radiation therapy or targeted drug therapy.

In some cases you may choose not to undergo treatment. For instance, you may feel that the side effects of treatment will outweigh the potential benefits. When that's the case, your doctor may suggest comfort (palliative) care to treat only the symptoms the cancer is causing, such as pain.

Treatment options for non-small cell lung cancers
Stage	Common options
I	Surgery
II	Surgery, chemotherapy, radiation
IIIA	Combined chemotherapy and radiation, sometimes surgery based on results of treatment
IIIB	Chemotherapy, sometimes radiation
IV	Chemotherapy, targeted drug therapy, clinical trials, supportive care

Treatment options for small cell lung cancers
Stage	Common options
Limited	Combined chemotherapy and radiation, sometimes surgery
Extensive	Chemotherapy, clinical trials, supportive care

Surgery
During surgery your surgeon works to remove the lung cancer and a margin of healthy tissue. Procedures to remove lung cancer include:

• Wedge resection to remove a small section of lung that contains the tumor along with a margin of healthy tissue
• Lobectomy to remove the entire lobe of one lung
• Pneumonectomy to remove an entire lung

If you undergo surgery, your surgeon may also remove lymph nodes from your chest in order to check them for signs of cancer. If your lymph nodes contain cancer cells, this usually indicates that cancer has spread, even if cancer hasn't been detected outside of your chest.

Lung cancer surgery carries risks, including bleeding and infection. Expect to feel short of breath after lung surgery. Your lung tissue will expand over time and make it easier to breathe. You may also feel pain in the muscles of your chest and in your arm on the side where you had the operation. Your doctor may recommend physical therapy or a rehabilitation program to help you restore your strength and range of motion.

Chemotherapy
Chemotherapy uses drugs to kill cancer cells. One or more chemotherapy drugs may be administered through a vein in your arm (intravenously) or taken orally. A combination of drugs usually is given in a series of treatments over a period of weeks or months, with breaks in between so that your body can recover.

Chemotherapy can be used as a first line treatment for lung cancer or as additional treatment after surgery. In some cases, chemotherapy can be used to lessen side effects of your cancer.

Radiation therapy
Radiation therapy uses high-powered energy beams, such as X-rays, to kill cancer cells. Radiation therapy can be directed at your lung cancer from outside your body (external beam radiation) or it can be put inside needles, seeds or catheters and placed inside your body near the cancer (brachytherapy).

Radiation therapy can be used alone or along with other lung cancer treatments. Sometimes it's administered at the same time as chemotherapy. Radiation therapy can also be used to lessen side effects of lung cancer.

Targeted drug therapy
Targeted therapies are newer cancer treatments that work by targeting specific abnormalities in cancer cells. Targeted therapy options for treating lung cancer include:

• Bevacizumab (Avastin). Bevacizumab stops a tumor from creating a new blood supply. Blood vessels that connect to tumors can supply oxygen and nutrients to the tumor, allowing it to grow. Bevacizumab is usually used in combination with chemotherapy and is approved for advanced and recurrent non-small cell lung cancer. Bevacizumab carries a risk of severe bleeding.
• Erlotinib (Tarceva). Erlotinib blocks chemicals that signal the cancer cells to grow and divide. Erlotinib is approved for people with advanced and recurrent non-small cell lung cancer that haven't been helped by chemotherapy. Erlotinib side effects include a skin rash and diarrhea.

Clinical trials
Clinical trials are studies of new lung cancer treatment methods. You may be interested in enrolling in a clinical trial if lung cancer treatments aren't working or if your treatment options are limited. The treatments studied in a clinical trial may be the latest innovations, but they don't guarantee a cure. Carefully weigh your treatment options with your doctor. Your participation in a clinical trial may help doctors better understand how to treat lung cancer in the future.

Supportive (palliative) care
When treatments offer little chance for a cure, your doctor may recommend you avoid harsh treatments and opt for supportive care instead. If you're receiving supportive care, your doctor may treat any signs and symptoms you experience to make you feel more comfortable, but you won't receive treatment aimed at stopping your cancer. Supportive care allows you to make the most of your final weeks or months without enduring treatment side effects that can negatively impact your quality of life.

Prevention

There's no sure way to prevent lung cancer, but you can reduce your risk if you:

• Don't smoke. If you've never smoked, don't start. Talk to your children about not smoking, so they can understand how to avoid this major risk factor for lung cancer. Many current smokers began smoking in their teens. Begin conversations about the dangers of smoking with your children early, so they know how to react to peer pressure.
• Stop smoking. Stop smoking now. Quitting reduces your risk of lung cancer, even if you've smoked for years. Talk to your doctor about strategies and stop-smoking aids that can help you quit. Options include nicotine replacement products, medications and support groups.
• Avoid secondhand smoke. If you live or work with a smoker, urge him or her to quit. At the very least, ask him or her to smoke outside. Avoid areas where people smoke, such as bars and restaurants, and seek out smoke-free options.
• Test your home for radon. Have the radon levels in your home checked, especially if you live in an area where radon is known to be a problem. High radon levels can be remedied to make your home safer. For information on radon testing, contact your local department of public health or a local chapter of the American Lung Association.
• Avoid carcinogens at work. Take precautions to protect yourself from exposure to toxic chemicals at work. In the United States, your employer must tell you if you're exposed to dangerous chemicals in your workplace. Follow your employer's precautions. For instance, if you're given a face mask for protection, always wear it. Ask your doctor what more you can do to protect yourself at work. Your risk of lung damage from these carcinogens increases if you smoke.
• Eat a diet full of fruits and vegetables. Choose a healthy diet with a variety of fruits and vegetables. Food sources of vitamins and nutrients are best. Avoid taking large doses of vitamins in pill form, as there may be unknown harms. For instance, researchers hoping to reduce the risk of lung cancer in heavy smokers gave them beta carotene supplements. Results showed the supplements actually increased the risk of cancer in smokers.
• Drink alcohol in moderation, if at all. Limit yourself to one drink a day if you're a woman or two drinks a day if you're a man. Anyone age 65 and older should drink no more than one drink a day.
• Exercise. Aim to achieve at least 30 minutes of exercise on most days of the week. Check with your doctor first if you aren't already exercising regularly. Start out slowly and continue adding more activity. Biking, swimming and walking are good choices. Add exercise throughout your day — park farther away from work and walk the rest of the way or take the stairs rather than the elevator.