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Lung cancer is cancer that usually starts in the lining of the bronchi (the main airways of the lungs), but can also begin in other areas of the respiratory system, including the trachea, bronchioles, or alveoli. It is the leading cause of cancer death in both men and women. In 2012, about 226,120 new cases of lung cancer are expected, according to the American Cancer Society.
Lung cancers are believed to develop over a period of many years.
Nearly all lung cancers are carcinomas, a cancer that begins in the lining or covering tissues of an organ. The tumor cells of each type of lung cancer grow and spread differently, and each type requires different treatment.
Lung cancers are generally divided into two types:
- Non-small cell lung cancer is much more common than small cell lung cancer, accounting for about 85 to 90 percent of lung cancers. The three main kinds of non-small cell lung cancer are named for the type of cells in the tumor:
- Squamous cell carcinoma (also called epidermoid carcinoma). It often begins in the bronchi near the middle of the lungs.
- Adenocarcinoma usually begins along the outer edges of the lungs. It is the most common type of lung cancer in people who have never smoked (although it is still seen more often in current or former smokers).
- Large cell carcinomas are a group of cancers with large, abnormal-looking cells. These tumors may begin anywhere in the lungs and tend to grow quickly.
- Small cell lung cancer, sometimes called oat cell cancer because the cancer cells may look like oats when viewed under a microscope, grows rapidly and quickly spreads to other organs. There are two stages of small cell lung cancer:
- Limited. Cancer is generally found in only one lung. There may also be cancer in nearby lymph nodes on the same side of the chest.
- Extensive. Cancer has spread beyond the primary tumor in the lung into other parts of the body.
It is important to find out what kind of lung cancer a person has. The different types of carcinomas, involving different regions of the lung, may cause different symptoms and are treated differently.
The following are the most common symptoms for lung cancer. However, each individual may experience symptoms differently.
Lung cancer usually does not cause symptoms when it first develops, but symptoms often become present after the tumor begins growing. A cough is the most common symptom of lung cancer. Other symptoms include:
- Constant chest pain
- Shortness of breath
- Recurring lung infections, such as pneumonia or bronchitis
- Bloody or rust-colored sputum
- A tumor that presses on large blood vessels near the lung can cause swelling of the neck and face
- A tumor that presses on certain nerves near the lung causes pain and weakness in the shoulder, arm, or hand
- Fever for unknown reason
Like many other cancers, lung cancer can cause:
- Loss of appetite
- Loss of weight
- Pain in other parts of the body not affected by the cancer
- Bone fractures
Other symptoms can be caused by substances made by lung cancer cells, which is referred to as a paraneoplastic syndrome. For example, certain lung cancer cells produce a substance that causes a sharp drop in the level of sodium in the blood, which can cause many symptoms, including confusion and sometimes even coma.
None of these symptoms is a sure sign of lung cancer. Only a doctor can tell whether a patient's symptoms are caused by cancer or by another problem. Consult your doctor for a diagnosis.
A risk factor is anything that increases a person's chance of getting a disease such as cancer. Different cancers have different risk factors. Several risk factors make a person more likely to develop lung cancer:
- Smoking is the leading cause of lung cancer, with about 80 percent of lung cancer deaths thought to be a result of smoking.
Additional risk factors include:
- Secondhand smoke. This refers to breathing in the smoke of others.
- Radon. A radioactive gas that cannot been seen, tasted, or smelled. It is produced by the natural breakdown of uranium. High levels of radon may be found in some homes or other buildings, especially basements.
A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking or diet, family history, or many other things. Different diseases, including cancers, have different risk factors.
Although these factors can increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors.
Knowing your risk factors for any disease can help guide you to the appropriate actions, including changing behaviors and being clinically monitored for the disease.
- Asbestos exposure
- Talc. While no increased risk of lung cancer has been found from the use of cosmetic talcum powder, some studies of talc miners and millers suggest a higher risk of lung cancer and other respiratory diseases from their exposure to industrial grade talc. Talcum powder is made from talc, a mineral which, in its natural form, may contain asbestos; however, by law, all home-use talcum products (baby, body, and facial powders) have been asbestos-free since 1973.
- Cancer-causing agents in the workplace, including:
- Radioactive ores such as uranium
- Vinyl chloride
- Nickel chromates
- Coal products
- Mustard gas
- Chloromethyl ethers
- Diesel exhaust
- Personal or family history of lung cancer
- Air pollution. In some cities, air pollution may slightly increase the risk of lung cancer.
In addition to a complete medical history to check for risk factors and symptoms, and a physical examination to provide other information about signs of lung cancer and other health problems, procedures used to diagnose lung cancer (or to help determine if it has spread) may include:
- Chest X-ray. This procedure looks for any mass or spot on the lungs.
- Computed tomography scan (also called a CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs such as the lungs. CT scans are more detailed than general X-rays.
- Sputum cytology. A study of phlegm (mucus) cells under a microscope.
- Thoracentesis. A hollow needle is inserted through the skin in the chest wall to remove fluid, which is then sent to the lab to be checked for cancer cells.
- Needle biopsy. A thin, hollow needle is guided into the mass while the lungs are being viewed on a flouroscopy or CT scan, and a sample of the mass is removed and evaluated in the pathology laboratory under a microscope.
- Bronchoscopy. The examination of the bronchi (the main airways of the lungs) using a flexible tube (bronchoscope) passed down the mouth or nose. Bronchoscopy helps to evaluate and diagnose lung problems, assess blockages, obtain samples of tissue and/or fluid, and/or to help remove a foreign body.
- Endobronchial ultrasound. An exam in which a bronchosope with a small ultrasound transducer on its tip is passed down the windpipe to look at lymph nodes in the mediastinum (the space between the lungs). If enlarged lymph nodes are seen, a small needle can be passed down the bronchoscope and through the wall of the airway to get samples of the nodes for testing.
- Mediastinoscopy. A process in which a small cut is made in the neck so that a tissue sample can be taken from the lymph nodes (mediastinal nodes) along the windpipe and the major bronchial tube areas to evaluate under a microscope.
- Thoracoscopy. A proceedure in which a small cut is made in the side of the chest wall through which a small tube with a video camera on the end is inserted. This allows the doctor to look at the outer part of the lungs and chest wall and to sample any abnormal areas for veiwing under a microscope.
- MRI, PET, or bone scans. These procedures are done to determine if the cancer has spread from where it started into other areas of the body.
Other tests and procedures may be used as well.
Specific treatment for lung cancer will be determined by your doctor based on:
- Your age, overall health, and medical history
- The type of lung cancer
- Extent of the disease
- Your tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disease
- Your opinion or preference
Depending on its type and stage, lung cancer may be treated with surgery, chemotherapy or other medications, radiation therapy, local treatments such as laser therapy, or a combination of treatments. Combination treatment or multimodality treatment refers to having more than one type of treatment.
Treatment for lung cancer includes one or more of the following:
- Surgery. Surgery is part of the treatment for early stage lung cancers. The type of surgery depends on the size and location of the tumor in the lung, the extent of the cancer, the general health of the patient, and other factors. Many surgeries are done with a long incision in the side of the chest, known as a thoracotomy. Some early stage tumors may be treated with video assisted thoracic surgery (VATS), which uses several small incisions (instead of one large one) and special long surgical tools. Types of surgery include:
- Segmental or wedge resection. Removal of only a small part of the lung.
- Lobectomy. Removal of an entire lobe of the lung.
- Pneumonectomy. Removal of an entire lung.
- Sleeve resection. Removal of a piece of bronchus, after which the lung is reattached to the remaining part of the bronchus.
- Radiation therapy. Radiation therapy is the use of high-energy radiation to kill cancer cells and to shrink tumors. Radiation may also be used with chemotherapy to treat lung cancer. There are two ways to deliver radiation therapy:
- External radiation (external beam therapy). A treatment that precisely sends high levels of radiation directly to the cancer cells. The machine is controlled by the radiation therapist. Since radiation is used to kill cancer cells and to shrink tumors, special shields may be used to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.
- Internal radiation (brachytherapy, implant radiation). Radiation is given inside the body as close to the cancer as possible. Substances that produce radiation, called radioisotopes, may be swallowed, injected, or implanted directly into the tumor. Some of the radioactive implants are called seeds or capsules. Internal radiation involves giving a higher dose of radiation in a shorter time span than with external radiation. Some internal radiation treatments stay in the body temporarily. Other internal treatments stay in the body permanently, though the radioactive substance loses its radiation within a short period of time. In some cases, both internal and external radiation therapies are used.
- Chemotherapy. The use of anticancer drugs to treat cancerous cells. In most cases, chemotherapy works by interfering with the cancer cell’s ability to grow or reproduce. Different groups of drugs work in different ways to fight cancer cells. The oncologist will recommend a treatment plan for each individual. Chemotherapy may be given before other treatments, after other treatments, or alone for lung cancer.
- Photodynamic therapy (PDT). A type of laser treatment that involves injecting photosensitizing chemicals into the bloodstream. Cells throughout the body absorb the chemicals. The chemicals collect and stay longer in the cancer cells than in the healthy cells. At the right time, when the healthy cells surrounding the tumor may already be relatively free of the chemical, the light of a laser can be focused directly on the tumor. As the cells absorb the light, a chemical reaction destroys the cancer cells. For lung cancer, the light is delivered through a bronchoscope (a small, flexible tube with a light on the end) that is inserted through the mouth or nose.
- Targeted therapy. These are drugs that target specific parts of cancer cells or nearby cells that help them grow. So far, these drugs have only been found to be useful for some non-small cell lung cancers. For example, as cancers grow, they form new blood vessels which nourish them. Research aimed at blocking the growth of these blood vessels has led to the development of medications called antiangiogenesis medications. Bevacizumab (Avastin) is one of these medications. It has been found to be helpful in prolonging the survival of some patients with advanced lung cancer. It is used with the standard chemotherapy regimen. Medications with other specific targets, such as crizotinib (Xalkori), erlotinib (Tarceva), and cetuximab (Erbitux), may also be useful.
There are specific names for the order in which treatment is given. Neoadjuvant treatment refers to having radiation or chemotherapy before surgery. Having one or both of these before surgery may help shrink the tumor, as a smaller tumor is easier to take out in surgery.
Chemotherapy or radiation soon after surgery is called adjuvant treatment. The goal of adjuvant treatment is to kill any cancer cells that may be left after the surgery. Even if there is no sign of cancer cells, your doctor may suggest adjuvant treatment, as it may lower the risk that the cancer will come back or spread.
Clinical trials are being conducted on prevention and treatment options for lung cancer, including photodynamic therapy and chemoprevention.
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