Cancer is a disease characterized by the uncontrolled growth of abnormal cells. Lung cancer is any type of malignant (cancerous) growth in the lungs. Lung cancer is the most common cause of cancer death in both men and women. There will be 158,000 estimated deaths from lung cancer in 1999, which represents 28 percent of all cancer deaths. (Source: The American Cancer Society)
The lung is the main organ of the respiratory system. Its main function is respiration (the exchange of gases between the environment and the body). Air enters the nose where it is filtered, warmed and humidified. After passing through the trachea (windpipe), the air travels into the lungs and through the tracheobronchial system, which consists of the bronchi (a system of branching airway tubes that become smaller as they reach deeper into the lung), the bronchioles (the smallest of the bronchi) and the alveoli (balloon-like sacs located at the end of the bronchi). Within the lungs and the tracheobronchial system is a lining called the epithelium, and within the epithelium are cells. The function of the cells is to divide, reproduce and repair worn-out or injured lung tissue and to allow for growth. If the cells lose their ability to control division, excess growth takes place, tumors form, and lung cancer emerges. There are four main types of lung cancer - adenocarcinoma, squamous cell carcinoma, small cell carcinoma and large cell carcinoma. The type of lung cancer is determined by the appearance of the cancerous cells under a microscope.
The number one cause of lung cancer is cigarette smoking, representing 85 to 90 percent of all cases. Other causes include exposure to radon, asbestos, nickel, chloromethyl ether, chromium, beryllium and arsenic (a byproduct of copper), as well as exposure to passive smoke or "secondhand" smoke. A person is "at risk" of developing lung cancer if they:
Lung cancer often does not produce symptoms in the early stages. When symptoms do occur, they are a result of tumor growth, pressure and invasion on nearby structures and nerves, regional growths or metastasis. If the cancer originated and grew in the bronchi and spread to nearby lymph nodes, the symptoms may include:
If the cancer originated and grew at the top of the lung, the symptoms may include:
If the cancer has metastasized and traveled to other parts of the body, the symptoms may include:
Additionally, lung tumors also may alter the production of hormones (called Paraneoplastic syndrome) that regulate body functions, causing:
If lung cancer is suspected, the person will have their medical history taken, a physical examination, and a variety of tests to confirm the diagnosis. During the physical exam, the doctor will look for lymph node enlargement in the neck or in the region above the collarbones, liver enlargement, abnormal abdominal enlargement, and signs of a lung mass. Simple hand palpitations (lightly pressing of areas) are used to find enlargements, while a stethoscope is used to detect lung mass. The doctor will listen for decreased breath sounds, unusual lung noises and areas of dullness in the lung. The tests may include the following:
Once the diagnosis of lung cancer is made, further staging studies are done to determine the spread of the disease and the appropriate treatment method. These studies include computed tomography (CT or CAT scan), a bone scan and a pulmonary angiography. The CT/CAT scan is a series of x-rays taken as a scanner revolves around the body. A computer then receives the x-ray images and creates a cross-sectional picture of the area being examined. A bone scan, also called a radionuclide or nuclear medicine scan, involves injecting a radioactive substance into the body. An instrument then scans the body to measure radiation levels. A pulmonary angiography is an x-ray procedure in which a substance (visible to an x-ray) is injected into the blood vessels leading to the lung. The lungs are then visible to the doctor for examination. Once the additional tests are done, the doctor will determine what stage the cancer is in and base treatment decisions on this information.
Standard treatment for patients with lung cancer is of limited effectiveness in all but the most localized tumors. For this reason, patients are encouraged to consider participating in clinical trials (research studies) designed to evaluate new approaches to therapy. Surgery, radiation therapy and chemotherapy (used alone or in various combinations) are the standard methods used to treat lung cancer. The choice of treatment depends on many factors, including the type of tumor, the extent of the disease when it is diagnosed, the age and general health of the patient and other variables. Surgical procedures that may be employed include wedge or segmental resection (removal of a portion of the affected lungs), lobetomy (removal of the entire lobe of the lung) or pneumonectomy (removal of the entire right or left lung). Radiation therapy is usually given by external beam, using machines located outside the body that deliver x-rays or electrons to the location of the tumor. The radiation dose is based on the size and location of the tumor. Some patients first receive external therapy to a wide area that includes the primary tumor and surrounding tissue. After the initial treatments, a smaller area is treated and a final treatment area that may be quite small. Radiation here is referred to as a "boost." Like surgery, radiation therapy is called local treatment, because it affects only the cells in the area being treated. Chemotherapy (treatment with anticancer drugs) is a systemic treatment - the drugs enter the bloodstream and travel through the body, affecting cancer cells outside the lung area. Drugs given to treat lung cancer may be given by mouth or injection to a muscle or vein. Some drugs require patients to stay in the hospital for a few days while doctors monitor the effects. Other drugs may be taken on an outpatient basis, at the doctor's office or at home.
What type of cancer is it? Are there tests to identify if the cancer has spread? Is surgery indicated? Will chemotherapy or radiation therapy be used in your treatment regime? What are the benefits and risks of the treatment options? Should participating in clinical trials be considered? What is the short and long term prognosis?