HEALTH: LUNG CANCER - SYMPTOMS & TREATMENT Bronchitis>>
What is Lung Cancer?
Lung cancer is cancer that begins in the lungs, the two organs found in the chest that help you breathe.
The lungs are made up of areas called lobes. The right lung has three lobes; the left lung has two, so there's room for the heart. When you breathe, air goes through your nose, down your windpipe (trachea), and into the lungs where it spreads through tubes called bronchi. Most lung cancer begins in the cells that line these tubes.
Lung cancer affects more than 200,000 Americans each year. Although cigarette smoking is the main cause, anyone can develop lung cancer. Lung cancer is always treatable, no matter the size, location, or if the cancer has spread.
The lung absorbs oxygen from the air and bring the oxygen into the bloodstream for delivery to the rest of the body. As the body’s cells use oxygen, they release carbon dioxide. The bloodstream carries carbon dioxide back to the lungs, and the carbon dioxide leaves the body when people exhale. The lung contains many different types of cells. Most cells in the lung are epithelial cells. Epithelial cells line the airways and produce mucus, which lubricates and protects the lung. The lung also contains nerve cells, hormone-producing cells, blood cells, and structural or supporting cells.
There are two major types of lung cancer: non-small cell and small cell. Non-small cell lung cancer (NSCLC) arises from epithelial cells and is the most common type. Small cell lung cancer begins in the nerve cells or hormone-producing cells of the lung. The term “small cell” refers to the size and shape of the cancer cells as seen under a microscope. It is important for doctors to distinguish NSCLC from small cell lung cancer because the two types of cancer are usually treated in different ways.
Lung cancer begins when cells in the lung grow out of control and form a lump (also called a tumor, mass, lesion, or nodule). A tumor can be benign (noncancerous) or malignant (cancerous). A cancerous tumor is a collection of a large number of cancer cells that have the ability to spread to other parts of the body. A lung tumor can begin anywhere in the lung.
Once a cancerous lung tumor begins to grow, it may or may not shed cancer cells. These cells can be carried away in blood or float away in the natural fluid, called lymph, which surrounds lung tissue. Lymph flows through tubes called lymphatic vessels that drain into collecting stations called lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes are located in the lungs, the center of the chest, and elsewhere in the body. The natural flow of lymph out of the lungs is toward the center of the chest, which explains why lung cancer often spreads there. When a cancer cell leaves its site of origin and moves into a lymph node or to a far away part of the body through the bloodstream, it is called metastasis.
The location and size of the initial lung tumor, and whether it has spread to lymph nodes or more distant sites, determines the stage of lung cancer. The type of lung cancer (NSCLC versus small cell) and stage of the disease (discussed later in Staging) determine what type of treatment is needed.
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Also see: Emphysema Bronchitis Asthma Allergies Pneumonia Sinuses Common Cold Influenza/Flu Swine Flu
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Health: Risk Factors of Lung Cancer (Lungs)
Screening
A risk factor is anything that increases a person’s chance of developing cancer. Some risk factors can be controlled, such as smoking, and some cannot be controlled, such as age and family history. Although risk factors can influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and communicating them to your doctor may help you make more informed lifestyle and health care choices.
The following factors may raise a person’s risk of developing lung cancer:
Tobacco. Most lung cancer occurs in people who smoke. Tobacco smoke damages cells in the lungs, causing the cells to grow abnormally. The risk that smoking will lead to cancer is higher for people who smoke heavily and/or for a long time. Regular exposure to smoke from someone else’s cigarettes, cigars, or pipes (called environmental or “secondhand” tobacco smoke) can increase a person’s risk of lung cancer even if that person does not smoke.
Asbestos. These are hair-like crystals found in many types of rock and are often used as fireproof insulation in buildings. When asbestos fibers are inhaled, they can irritate the lung. Many studies show that the combination of smoking and asbestos exposure is particularly hazardous. People who work with asbestos in jobs (such as shipbuilding, asbestos mining, insulation, or automotive brake repair) and smoke have a higher health risk of developing lung cancer. Using protective breathing equipment reduces this health risk.
Radon. This is an invisible, odorless gas naturally released by some soil and rocks. Exposure to radon has been associated with an increased health risk of some types of cancer, including lung cancer. Most hardware stores have kits that test home radon levels, and basements can be ventilated to reduce radon exposure.
There are no tests recommended for screening the general population for lung cancer. Doctors still need to prove that screening everyone at risk for lung cancer reduces rates of death from lung cancer in the general population. A new test, called a low-dose helical (or spiral) computed tomography (CT or CAT) scan, is currently being studied for this purpose. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail.
Health: Symptoms of Lung Cancer (Lungs)
People with lung cancer may experience the following symptoms. Sometimes people with lung cancer do not show any of these symptoms. Or, these symptoms may be caused by a health condition that is not cancer. If you are concerned about a symptom on this list, please talk with your doctor.
For people with lung cancer who have no symptoms, their lung cancer may be discovered on a chest x-ray or CT scan performed for some other reason, such as checking for heart disease. Most people with lung cancer are diagnosed when the tumor grows, takes up space, or begins to interfere with nearby structures. A lung tumor may also make fluid that can collect in the lung or the space around the lung. A tumor can push the air out of the lungs and cause the lung to collapse. In this way, a lung tumor can prevent the exchange of oxygen and carbon dioxide by blocking the flow of air into the lungs, or by using up the space normally required for oxygen to come in and carbon dioxide to go out of the lung.
Symptoms of lung cancer may include:
- Fatigue
- Cough
- Shortness of breath
- Chest pain, if a tumor invades a structure within the chest or involves the lining of the lung
- Loss of appetite
- Coughing up phlegm or mucus
- Hemoptysis (coughing up blood)
Although lung cancer can metastasize (spread) anywhere in the body, the most common sites of spread are the lymph nodes, lungs, bones, brain, liver, and structures near the kidneys called the adrenal glands. Metastases (spread to more than one area) from lung cancer can cause further breathing difficulties, bone pain, abdominal or back pain, headache, weakness, seizures, and/or speech difficulties. Rarely, a lung tumor can release hormones that result in chemical imbalances, such as low blood sodium levels or high blood calcium levels.
Symptoms such as fatigue, malaise (feeling out-of-sorts or unwell), and loss of appetite are not necessarily due to metastases. The presence of cancer anywhere in the body can cause a person to feel unwell in a general way. Loss of appetite can result in weight loss. Fatigue and weakness can further worsen breathing difficulties.
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Doctors use many tests to diagnose cancer and determine if it has spread from the lung. Some tests may also determine which treatment may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible or more information is needed, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized, but they can never be used to diagnose lung cancer. Only a biopsy can do that. Your doctor may consider these factors when choosing a diagnostic test:
- Location of the suspected cancer
- Size of the suspected cancer
- Age and health condition
- The type of cancer suspected
- Severity of symptoms
- Previous test results
In addition to a physical examination, the following tests may be used to diagnose lung cancer:
Biopsy. A biopsy is the only way to make a diagnosis of lung cancer. A biopsy is the removal of a small amount of tissue for examination under a microscope. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). If cancer cells are present, the pathologist will determine if it is small cell lung cancer or NSCLC, based on its appearance under the microscope.
Common procedures doctors use to obtain tissue for the diagnosis and staging of lung cancer are listed below:
Sputum cytology. If there is reason to suspect lung cancer, the doctor may ask a person to cough up some phlegm so it can be examined under the microscope. A pathologist can find cancer cells mixed in with the mucus.
Bronchoscopy. In this procedure, the doctor passes a thin, flexible tube with a light on the end into the mouth or nose, down through the main windpipe, and into the breathing passages of the lungs. A surgeon or a pulmonologist (a medical doctor who specializes in the diagnosis and treatment of lung disease) may perform this procedure. The tube lets the doctor see inside the lung. Tiny tools inside the tube can take samples of fluid or tissue, so the pathologist can examine them. Patients are given mild anesthesia (medication to put them to sleep) during a bronchoscopy.
Needle aspiration. After numbing the skin, a special type of radiologist, called an interventional radiologist, inserts a small needle through the chest and directly into the lung tumor. The doctor uses the needle to aspirate (suck out) a small sample of tissue for testing. Often, the radiologist uses a chest CT scan or special x-ray machine called a fluoroscope to guide the needle.
Bone marrow biopsy. For patients with small cell lung cancer, doctors sometimes use a local anesthetic (to numb the area) and a special needle to remove a tiny piece of bone (typically from the hip bone) in order to determine whether small cell cancer is present within the bones.
Thoracentesis. After numbing the area, a needle is inserted through the chest wall and into the space between the lung and the wall of the chest where fluid can collect. The fluid is removed and checked for cancer cells by the pathologist.
Thoracotomy. This procedure is performed in an operating room with the help of general anesthesia. A surgeon then makes an incision in the chest, examines the lung directly, and takes tissue samples for testing. A thoracotomy is the procedure surgeons most often perform to completely remove a lung tumor.
Thoracoscopy. Through a small cut in the skin of the chest wall, a surgeon can insert a special instrument and a small video camera to assist in the examination of the inside of the chest. Patients require general anesthesia, but recovery time may be shorter given the smaller incisions. This procedure may be referred to as “VATS” (video-assisted thoracoscopic surgery).
Mediastinoscopy. A surgeon examines and takes a sample of the lymph glands in the center of the chest (underneath the breastbone) by making a small incision at the top of the breastbone. This procedure also requires general anesthesia and is done in an operating room.
Imaging tests
In addition to biopsies and surgical procedures, imaging scans are vital to the care of people with lung cancer. However, no test is perfect, and no scan can diagnose lung cancer. Only a biopsy can do that. Chest x-ray and scan results must be combined with a person’s medical history, a physical examination, blood tests, and biopsy information to form a complete story about where the cancer began and whether or where it has spread.
CT scan. This test produces images that allow doctors to see the size and location of lung tumors and/or lung cancer metastases.
Magnetic resonance imaging (MRI) scan. This test also produces images that allow doctors to see the size and location of lung tumors and/or lung cancer metastases. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium (a special dye) may be injected into a patient’s vein to provide better detail. MRI scanning is imprecise when used to image a structure that is moving, like your lungs, which move with each breath a person takes. For that reason, the MRI scan is rarely used to study the lungs themselves.
Scans are also available that use radioactive molecules, called tracers, injected into the blood to show where cancer is possibly located:
Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images. A specialist in nuclear medicine helps your doctor interpret PET scans.
Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by cancer, appear dark.
Bone scans and PET scans are often used in combination with information gathered from a CT scan, MRI, regular x-rays, and a physical examination.
Finding out where the cancer started
Lung cancer starts in the lung. Many other types of cancer start elsewhere in the body and spread to the lungs when they metastasize. For example, breast cancer that has spread to the lungs is still called breast cancer. Therefore, it is important for doctors to know if cancer started in the lung or elsewhere.
To find where the cancer started, the doctor takes into account the patient’s symptoms and medical history, physical examination, the appearance of the tumor on x-rays and scans, and risk factors for cancer. A pathologist can perform tests on the biopsy sample to help identify the origin of a cancer, and the doctor may order other tests for the patient to rule out specific types of cancer. If, after these considerations, the doctor is still not sure where the cancer started, the doctor may give a diagnosis of metastatic cancer “of unknown primary.” Most treatment for metastatic cancer of unknown primary that are first discovered in the chest are the same as those for metastatic lung cancer.
