Lung cancer, also known as carcinoma of the lung or pulmonary carcinoma, is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. Lung cancer is one of the most common cancers in the world. It is a leading cause of cancer death in men and women in the United States.
Defining Lung Cancer
Lung Cancer is caused by the abnormal growth of cells in a person's lungs, resulting in a malignant tumor. Malignant tumors of this type can, 'Metastasize,' or spread throughout the person's body through their bloodstream or lymphatic system. Lung cancer is very life-threatening because it has a tendency to metastasize early in its course, and is one of the most difficult forms of cancer to treat. Lung cancer has the ability to spread to any organ in the body, although some organs are more commonly affected; such as the liver, brain, and adrenal glands. Lung cancer commonly affects the person's bones as well.
Other forms of cancer can metastasize to the lungs from other parts of the body. Tumors comprised of the same form of cells as the original tumor from another form of cancer such as Prostate Cancer can spread through the bloodstream to the lungs. Should this occur, it is metastatic Prostate Cancer in the lung, not Lung Cancer.
The lung's primary function is the exchange of gases between the air a person breathes and the blood in their body. The lungs remove carbon dioxide from their bloodstream. The lungs, 'inspire,' oxygen from the air a person breathes into their bloodstream. A person's right lung has three lobes. Their left lung has two of these lobes and a small structure called the, 'Lingula.' There are major airways that enter the lungs called the, 'Bronchi,' that arise from the person's, 'Trachea.' The Bronchi branch into smaller and smaller airways that are referred to as, 'Bronchioles,' ending in very small sacs called, 'Alveoli.' The Alveoli are where the exchange of gases occurs in the persons lungs. A person's chest wall and the lungs themselves are covered with a very thin layer of tissue referred to as the, 'Pleura.'
Ninety to ninety-five percent of lung cancers are believed to begin in the lining cells of the Bronchi and Bronchioles; although Lung Cancer can begin anywhere in a person's lungs. Because of this, Lung Cancer is referred to as, 'Bronchogenic Cancer, or , 'Bronchogenic Cancinoma,' on occasion. There is a potential for cancer to begin from the Pleura, which is called, 'Mesothelioma,' or on rare occasion, from the supporting tissues within the person's lungs such as their blood vessels.
Incidence of Lung Cancer
Lung Cancer has surpassed Breast Cancer as the cause of the most cancer-related deaths among women in America. Lung Cancer is the form of cancer that has caused the most deaths in both men and women throughout the entire world. The American Cancer Society estimated that 215,000+ new cases of Lung Cancer were diagnosed, and 161,840 deaths caused by Lung Cancer occurred in 2008. The United States National Cancer Institute has stated that about 1 in every 14 men and women in America will face a diagnosis of Lung Cancer at some point in their life.
Lung Cancer is largely a disease found in persons who are Seniors. Nearly seventy-percent of persons who are diagnosed with Lung Cancer are over the age of sixty-five; less than three-percent of persons with this diagnosis are persons under the age of forty-five. Lung Cancer itself was uncommon before the 1930's, but increased dramatically in the years afterward due to an increase in smoking.
Causes of Lung Cancer
Tobacco smoke contains more than four-thousand chemical compounds. Many of these compounds have been demonstrated to cause cancer and are referred to as, 'Carcinogenic.' There are two main Carcinogens in tobacco smoke; they are chemicals known as, 'Polycyclic Aromatic Hydrocarbons,' and, 'Nitrosamines.' A person's risk of developing Lung Cancer decreases every year after they have quit smoking as healthy cells begin to grow and replace cells that have been damaged in their lungs. After approximately fifteen years of not smoking, the risk of developing Lung Cancer in former smokers approaches that of a non-smoker.
Lung Cancer is very strongly tied to cigarette smoking. Ninety-percent of Lung Cancers begin as a result of using tobacco, and the risk of Lung Cancer increases with the number of cigarettes a person smokes over time. Doctors rate a person's risk for Lung Cancer in terms of, 'Pack-Years.' For example; if a person has smoke two packs of cigarettes each day for ten years, they are considered to have a twenty, 'Pack-Year,' smoking history. The risk of Lung Cancer is increased with a ten, 'Pack-Year,' history, and persons with a thirty, 'Pack-Year,' history are considered to be at greatest risk for developing Lung Cancer. Out of persons who smoke two or more packs of cigarettes each day, approximately one out of seven of them will die from Lung Cancer.
Cigar and Pipe smokers may develop Lung Cancer as well, although the risk is not as great as it is for persons who smoke cigarettes. Persons who smoke cigarettes have a risk of developing Lung Cancer that is twenty-five times greater than a non-smoker. People who smoke cigars or a pipe have a risk of Lung Cancer that is five-times greater than a non-smoker.
Passive Smoking involves the inhalation of tobacco smoke from smokers, and is an established risk factor for the development of Lung Cancer. Non-smokers who live with a person who smokes have a twenty-four percent increase in their risk of developing the disease compared to non-smokers who do not live with a smoker. Approximately 3,000 people die each year in America from Lung Cancer that is attributed to passive smoking.
Asbestos Fibers are silicate fibers, and once in a person's lungs they can stay there for the person's lifetime. Places of work are a common source of exposure to these fibers, where they were used in the past as both acoustic and thermal insulation. Asbestos is either limited or banned entirely in many nations today, to include America. Mesothelioma, as well as other forms of Lung Cancer, has been associated with asbestos exposure. Persons who have been exposed to asbestos fibers and who smoke have a dramatically increased risk of Lung Cancer. Persons who worked with asbestos, but do not smoke, have five-times the risk of developing Lung Cancer. Persons who worked with asbestos and smoke have a fifty to ninety percent increased risk of developing Lung Cancer than a non-smoker.
Radon Gas is a chemically inert, natural gas which is a natural decay product of uranium; it emits a type of ionizing radiation. Radon gas is known to cause Lung Cancer. Twelve-percent of the deaths from Lung Cancer are attributed to Radon gas, around 15,000 to 22,000 people die from Lung Cancer caused by Radon gas each year in America. Radon gas is the second leading cause of Lung Cancer in America. Radon gas has the ability to travel through soil and into people's homes through gaps in pipes, drains, the foundation of the home or additional openings. The Environmental Protection Agency has estimated that one in fifteen homes in America have dangerous levels of Radon gas, which is odorless and invisible. Radon gas can be detected with easy-to-use test kits.
Genetics may play a part in Lung Cancer; a number of studies have shown that Lung Cancer is more likely to develop in both smoking and non-smoking relatives of persons who have experienced Lung Cancer than in person among the general population. There is a region on the long arm of chromosome six that research has found to be likely to carry a gene associated with increased susceptibility for development of Lung Cancer in persons who smoke.
Certain lung diseases such as Chronic Obstructive Pulmonary Disease (COPD), are associated with an increased risk for developing Lung Cancer. Persons with COPD have a risk of developing Lung Cancer that is four to six times greater than a non-smoker.
A Prior History of Lung Cancer
Persons who have survived Lung Cancer have a greater risk of developing another Lung Cancer. Persons who have survived a, 'Non-Small Cell Lung Cancer,' (NSCLC) have a risk of one to two percent each year of developing another Lung Cancer. Persons who have survived a, 'Small-Cell Lung Cancer,' (SCLC) have a risk approaching six-percent each year of developing another Lung Cancer.
Air pollution caused by industry, power plants and vehicles of various types raises the likelihood of developing Lung Cancer in persons who are exposed polluted air. Approximately one-percent of the deaths from Lung Cancer are attributed to breathing polluted air. Prolonged exposure to air pollution may carry risks for developing Lung Cancer which are similar to Passive Smoking; according to experts.
Types of Lung Cancer
Lung Cancers are divided into two classifications based on the type of tumor cells. The two types of cancers grow and spread differently. They have different treatments, and distinguishing between them is important.
Small-Cell Lung Cancer (SCLC) exists in approximately twenty-percent of persons with Lung Cancer. SCLC is the most aggressive and rapidly-growing form of Lung Cancer, and is very strongly related to cigarette smoking. SCLC only occurs in non-smokers one-percent of the time. SCLC metastasizes very quickly to other sites in the person's body, and by the time it is discovered it may have already spread extensively. SCLC is sometimes referred to as, 'Oat-Cell Carcinoma,' due to its appearance under a microscope.
Non-Small Cell Carcinomas (NSCLC's) are the more common form of Lung Cancer. Approximately eighty-percent of Lung Cancers are NSCLC's. There are three main types of NSCLC's, named according to the types of cells which are found in the tumors.
Adenocarcinomas: The most common type of NSCLC in America is Adenocarcinoma, comprising approximately fifty-percent of Lung Cancers. Adenocarcinomas are associated with smoking, although non-smokers who develop Lung Cancer also develop Adenocarcinomas.
Squamous Cell Carcinomas: Squamous Cell Carcinomas account for approximately thirty-percent of NSCLC's, and used to be more common than Adenocarcinomas. Squamous Cell cancers usually arise in a person's Bronchi.
Large Cell Carcinomas: Large Cell Carcinomas are the least common form of NSCLC. They are referred to as, 'Undifferentiated Carcinomas,' at times.
Mixed NSCLSC: Sometimes, mixtures of different types of NSCLC's occur.
Five to ten-percent of Lung Cancers consist of, 'Other Types,' of cancers which are less common than NSCLC's and SCLC's.
Bronchial Carcinoids: Five-percent of Lung Cancers are Bronchial Carcinoids, consisting of tumors which are generally small; three to four centimeters or less in size when the person is diagnosed. These tumors usually occur in persons who are under forty years of age and are not related to cigarette smoking. Carcinoid tumors may metastasize. A small number of carcinoid tumors secrete substances which are hormone-like, potentially causing symptoms that are related to the hormone being produced. Carcinoids usually both grow and spread slower than Bronchogenic forms of cancer. Fortunately, Carcinoids are often times detected early, and are able to be surgically removed.
Supporting Lung Tissue Cancer: Cancer of the supporting tissues of the lungs, such as blood vessels, or the smooth muscles, or cells involved in the person's immune response may occur on rare occasion.
Metastatic Cancers: Metastatic cancers from other tumors in a person's body, attributed to another from of cancer, can often be found in their lungs. Through the bloodstream, tumors from anywhere in a person's body can spread to their lungs, as well as through their lymphatic system. Metastatic tumors in the lungs are many times multiple, as well as being concentrated in the person's peripheral areas in the lungs rather than in the central areas.
Signs and Symptoms of Lung Cancer
The symptoms a person will experience related to Lung Cancer vary depending on where the tumor is, and how widespread it is as well. Persons with Lung Cancer may experience a number of different symptoms, or none at all.
No Symptoms: Twenty-five percent of persons with Lung Cancer discover it through a routine chest X-ray or CT scan, presented as a solitary, small mass which is sometimes referred to as a, 'Coin Lesion.' They may report experiencing no symptoms at all when their cancer is discovered.
Cancer-Related Symptoms: Cancer growth, as well as invasion of the person's lung tissues and surrounding tissues, can interfere with their breathing. This can present symptoms including coughing, wheezing, chest pain, shortness of breath, and coughing up blood or, 'Hemoptysis.' There is a syndrome known as, 'Pancoast's Syndrome,' which involves cancer that has invaded nerves, causing shoulder pain which travels down the outside of the person's arm. The person may experience paralysis of their vocal cords that leads to hoarseness. They may experience, 'Dysphagia,' or difficulty swallowing due to an invasion of their Esophagus. If the person experiences a large airway obstruction, a portion of their lung may collapse and an infection could occur in the obstructed area.
Metastasis Symptoms: Lung Cancer which has spread to a person's bones can cause excruciating pain in the areas affected. If Lung Cancer has metastasized to the person's brain they may experience various Neurological symptoms including headaches, seizures, blurry vision, or even symptoms of a stroke including loss of sensation in parts of their body, or weakness.
Paraneoplastic Symptoms: Persons with Lung Cancer commonly experience symptoms due to production of hormone-like substances from tumor cells referred to as, 'Paraneoplastic Symptoms.' The syndromes are commonly associated with SCLC, although they may be found with any type of tumor. One of the more common Paraneoplastic Symptoms associated with SCLC is the production of a hormone called, 'Adrenocroticotrophic Hormone,' or, 'ACTH.' ACTH leads to over-secretion of a hormone called, 'Cortisol,' by the person's Adrenal Glands; a condition referred to as, 'Cushing's Syndrome.'
Non-Specific Symptoms: There are some, 'Non-Specific,' symptoms a person may experience in association with Lung Cancer. These symptoms include weakness, fatigue, weight loss, mood changes, and depression.
Reasons to Contact Your Doctor: A person should contact their Doctor or other health care provider if they have a persistent cough, or a chronic cough that has grown worse. The should also do so if they have blood in their sputum, persistent bronchitis, a repetitious respiratory infection, chest pain, unexplained weight loss or fatigue, breathing difficulty, shortness of breath, or wheezing.
Diagnosing Lung Cancer
There are a number of tests and diagnostic procedures used to diagnose lung cancer, including:
The Persons Physical Examination and History: These may reveal signs and symptoms of Lung Cancer, as well as identifying risks the person may have for Lung Cancer. Health care providers identify risks such as smoking, check for breathing difficulties, infection in the person's lungs, and any airway obstructions. They look for an sign of Cyanosis; a bluish color of the person's mucous membranes and skin caused by a lack of oxygen in their blood. The health care provider looks for changes in the tissues in the person's nail beds, which may indicate lung disease.
Chest X-ray: A chest X-ray is commonly the first diagnostic step when a new symptom of Lung Cancer is present. A chest X-ray can reveal any suspicious areas in the person's lungs, but it is unable to tell if they are cancerous. There are benign tumors known as, 'Harmatomas,' that can show up on a chest X-ray that mimic Lung Cancer.
CT Scan: A CT Scan is something that might be ordered if an X-ray does not show an abnormality, or provide enough information. Sometimes an intravenous contrast material is given before the CT Scan is done to help define the person's organs and their positions.
Low-Dose Helical CT Scan: A Low-Dose Helical CT Scan requires a special CT Scanner, and is an effective tool used for identification of small lung cancers in both smokers and ex-smokers.
Magnetic Resonance Imaging (MRI): MRI scanners may be used to provide precision details concerning the location of a tumor when needed. MRI scanners use radio waves, magnetism, and a computer to create images of the person's body structures.
Positron Emission Tomography (PET): PET scanners use short-lived radioactive drugs along with colorful, three-dimensional images of tissues in the person's body to observe the person's anatomical structures. PET scanners are able to measure the metabolic activity and function of tissues, and help to determine if a tumor is actively growing. PET scanners can help to determine the type of cells within a particular tumor.
Bone Scans: Bone Scans create images of a person's bones on a computer screen, or on film to help determine if Lung Cancer has metastasized the their bones. A small amount of radioactive material is injected into the person's bloodstream, where it collects in their bones; particularly around areas involved in metastatic tumors. The material is detected by a scanner; the image is recorded on a special film, and is available to the person's health care worker.
Sputum Cytology: The most inexpensive and risk-free diagnostic procedure involves collection of a sample of the person's sputum. It is also something a Pathologist will require for confirmation of malignant cells.
Bronchoscopy: Bronchoscopy involves viewing the person's airways through a thin, fiber-optic probe which is inserted through either their nose or mouth. A Bronchoscopy can show areas of the person's central areas in their lungs or larger airways that may have a tumor, and allow a health care worker to collect a sample or, 'Biopsy.' The person is usually sedated or under anesthesia for this procedure, which can be uncomfortable, and must be performed by a Lung Specialist.
Needle Biopsy: A Needle Biopsy involves, 'Fine Needle Aspiration,' or ,'FNA,' through the person's skin, often with radiological imaging guidance. Needle Biopsy can be useful in obtaining cells used in diagnosing tumor nodules in the person's lungs, especially when a tumor is not accessible through Bronchoscopy. The person is given a local anesthetic and a thin needle is inserted through their chest wall in the area of their lung where the tumor is located. Cells from the tumor are pulled into the syringe, and then examined under a microscope.
Thoracentesis: Lung Cancers may involve the Pleura, or lining tissue of the lungs, leading to accumulation of fluid between the person's lungs and their chest wall. Using a thin needle to collect a sample of this fluid, called a, 'Thoracentesis,' can reveal cancer cells in order to establish a diagnosis.
Major Surgery: Doctors will attempt other procedures first, but if none of the procedures mentioned present a diagnosis, surgical methods may be used to obtain tumor tissue in order to reach a diagnosis. One of the surgical procedures used is called a, 'Mediastinoscopy,' and involves surgically inserting a probe in order to biopsy a tumor. Another is referred to as a, 'Thoracotomy,' and involves opening the person's chest wall in order to either biopsy or remove a tumor.
Blood Testing: Blood tests by themselves cannot reach a diagnosis of Lung cancer. Blood testing can show either metabolic or biochemical abnormalities in a person's body which accompany cancer. Elevated levels of either Calcium or an enzyme called, 'Alkaline Phosphatase,' can accompany cancer that has metastasized to the person's bones. Elevated levels of enzymes such as, 'Aspartate Aminotransferase,' and, 'Alanine Aminotrasferase,' may be a sign of liver damage and the potential for the presence of a tumor which has metastasized.
Stages of Lung Cancer
Staging of Lung Cancer involves evaluation of the size of the cancer, as well as the presence or absence of metastases in the person's lymph nodes or other organs. Staging determines the treatment the person will receive, and in estimating their prognosis.
NSLC: NSLC Lung Cancers are assigned Stages One through Four in order of severity.
SCLC: SCLC Lung Cancer is staged in two tiers.
Treatment of Lung Cancer
Treatment of Lung Cancer may involve Radiation Therapy, Chemotherapy, Surgical Removal of the tumor, or a combination of these forms of treatment. Location of the tumor, the tumor's extent, and the overall health of the person are all taken into account when considering which form or forms of treatment are appropriate for them. Treatment may be aimed at either curing the cancer, or at reducing the person's pain and suffering. 'Adjuvant Therapy,' a form of therapy which is added in order to enhance the effects of primary therapy, includes Chemotherapy or Radiation Therapy, and may be used after a tumor is surgically removed to ensure that all tumor cells are killed.
Surgery: Surgery to remove a tumor is usually performed for persons with Stage One or Stage Two NSCLC. Approximately 10-35% of Lung Cancers may be removed surgically; however, removal of a tumor does not always result in cure of the cancer because tumors may have spread and can recur at a later time. Surgery may not be an option if the tumor is located to closely to the person's Trachea, or if the person has another serious condition. Surgery is performed less often for persons with SCLC because the tumors involved are less likely to be localized to one area.
Radiation therapy can be used to treat both SCLC and NSCLC, and involves using high-energy X-rays and/or other forms of radiation to kill cancer cells. Radiation is delivered externally to the person through the placement of sealed containers which have radioactive substances in them on the area where the tumor is located. 'Brachytherapy,' is a form of Radiation therapy where a small pellet of radioactive material is placed directly into the cancer, or into the person's airway next to the cancer, and is usually applied through a Bronchoscope. External Radiation Therapy can usually be performed on an outpatient basis. A, 'Gamma Knife,' is a form of external Radiation Therapy involving multiple beams of radiation which are focused over a person's head for several minutes to several hours. The person's head is held in place by a rigid frame during this procedure. The, 'Gamma Knife,' is used to treat Single Brain metastases. External Radiation Therapy is usually performed four or five days a week for several weeks.
Side-effects of Radiation Therapy can include a reduction of white blood cells which renders the person more susceptible to infections, as well as low blood platelet levels, making it more difficult for their blood to clot. Persons whose organs are being treated with Radiation Therapy may experience diarrhea, nausea, and vomiting. Radiation Therapy may irritate the person's skin in the area where the treatment is being applied, but the skin tends to improve over time after treatments have ended.
SCLC and NSCLC can both potentially be treated with Chemotherapy, which refers to the administration of medications designed to cease cancer cell growth by killing them or prevention of cancer cell division. Platinum-based Chemotherapy drugs have shown to be the most effective in treating Lung Cancer, although there are a number of Chemotherapeutic drugs. The treatment chosen most often for persons with SCLC is Chemotherapy because the tumors associated with SCLC are generally spread throughout the person's body when they are diagnosed. Approximately half of persons with SCLC survive for four months without Chemotherapy. With the use of Chemotherapy, their survival rate increases four to five times. Chemotherapy is not exceptionally effective in persons with NSCLC unless it has metastasized; then it can increase their survival rate.
Chemotherapy can be administered orally, intravenously, or in a combination of these ways. Chemotherapy is usually given on an outpatient basis in a series of treatments over a period of weeks to months. The side-effects of Chemotherapy can be unpleasant, and may include damage to blood cells resulting in increased risk of infection, difficulty clotting, bruising or bleeding easily, and fatigue. Other potential side-effects include hair loss, nausea, vomiting, weight loss, mouth sores and diarrhea. There are medications that have been developed to treat or prevent side-effects of Chemotherapy treatment, and the side-effects usually disappear during the person's recovery phase, or after completion of treatments.
Brain Prophylactic Radiation:
Many times, SCLC will spread to the person's brain. Persons with SCLC who are responding well to treatment are sometimes treated with Radiation Therapy to their head. This form of therapy may cause fatigue, memory problems, nausea, and additional side-effects.
Treatment of Lung Cancer Recurrence
Persons who experience a recurrence of Lung Cancer that is confined to one place in the lung might be treated through surgery. Relapsed tumors usually do not respond to the same Chemotherapy drugs that were used previously. There is a type of Chemotherapy that is referred to as, 'Second-line,' Chemotherapy which has proven to be effective at prolonging the survival of persons with a recurrence of Lung Cancer. Persons who are well enough to tolerate therapy may be candidates for experimental therapies or clinical trials.
There is a drug called, 'Erlotinib,' that is an alternative to standard Chemotherapy. Erlotinib can be used in persons with NSCLC who no longer respond to Chemotherapy; Erlotinib is taken orally, and is referred to as a, 'Targeted Drug,' because it specifically targets cancer cells. There are other drugs known as, 'Antiangiogenesis Drugs,' that block the development of new blood vessels within a cancer, removing the oxygen supply to it, and causing it to die. An example of these drugs includes, 'Bevacizumab,' which is administered intravenously every two or three weeks.
Photodynamic Therapy (PDT):
PDT is used for various types and stages of Lung Cancer, and involves using a photosynthesizing agent like porphyrin which is injected into the person's bloodstream a few hours before surgery. The agent deposits itself in rapidly growing cancer cells, and a physician uses a light with a specific wavelength during surgery that activates the agent, producing a toxin that destroys cells in the tumor. PDT is useful only in treatment of cancers that can be reached with a light source.
Radiofrequency Ablation (RFA):
RFA is under study as an alternative to surgery, notably in persons with early stage Lung Cancer. RFA involves using a needle which is inserted through the person's skin into the cancer, guided by a CT Scanner. Radio frequencies are transmitted through the needle, heating the tissues around the needle; killing cancerous tissue and closing off small blood vessels that supply the cancer.
Persons with Lung Cancer may be offered a number of different and new therapies which are still experimental involving new drugs being tested through clinical trials. There are experimental treatments called, 'Immunotherapies,' which are under study involving the use of vaccine-related therapies in an attempt to utilize a person's own immune system to fight against cancerous cells.
Lung Cancer Prognosis
The chance for to either prolong the life of a person with Lung Cancer, or achieve a cure, is dependent upon both the size of the cancer and its location, as well as other things. The type of Lung Cancer the person has, the symptoms they are experiencing, and their overall health also have bearing on their prognosis.
SCLC presents the most aggressive growth among all forms of Lung Cancer. Untreated, persons with SCLC have a median survival time of two to four months after being diagnosed. SCLC is also the type of Lung Cancer that is most responsive to Chemotherapy and Radiation Therapy. Of all persons with SCLC, only 5-10% is still alive five years after being diagnosed, and have survived Limited-Stage SCLC.
NSCLC in Stage One finds cancers that can be completely removed, and the five-year survival rate is approximately 75%. In Advanced Stages, overall survival rates are poor.
Overall, the prognosis for Lung Cancer is poor when compared to other forms of cancer. Overall survival rates for persons with Lung Cancer are approximately 16%. Persons with Colon Cancer have a survival rate of 65%, while persons with Breast Cancer have a survival rate of 89%, and men with Prostate Cancer have a survival rate of 99%.
The pearl, white, or clear has been designated as the ribbon color for lung cancer awareness. The original color was a clear ribbon. Some sources suggest clear or white as a subset of pearl for long-term-non-smoker/never-smoker lung cancer, but there's no evidence of lung cancer organization support for this distinction. Some lung cancer organizations may use different colors or symbols. The month of November has been officially declared Lung Cancer Awareness Month.
Common symptoms of lung cancer include:
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