Lung cancer occurs when a malignant (cancerous) tumor grows inside the lungs, in structures such as the bronchi (small tubes that connect the windpipe to the inner surfaces of the lungs where gas transfer takes place). Like many other types of cancer, lung cancer is capable of spreading (metastasizing) to other parts of the body. In this case, cancer beginning in the lungs most commonly spreads to the brain, bones, adrenal glands and liver, via any of three mechanisms: direct extension, via the blood vessels, or via the lymph system. Direct extension occurs when a tumor grows rapidly in size such that it begins to touch an adjacent organ or structure, and then begins to penetrate itself into that adjacent organ or structure. Tumor cells are also able to get into the blood and lymph circulatory systems and travel, one by one, to distant structures.
Lung cancer is now the most prevalent form of cancer affecting Americans with an estimated 222,500 new cases every year, according to the American Cancer Society (ACS, 2010). Beyond being the most common form of cancer, lung cancer is also often difficult to treat. As a result, lung cancer is the most deadly cancer with roughly 160,000 Americans dying from it every year. This is about 30% of all cancer deaths! (ACS, 2010).
Although lung cancer is difficult to treat and cure, it is for the most part preventable. Lifestyle choices can be made which can almost eliminate your risk for getting the disease. Your decision to stop smoking and to eat a healthy diet featuring plenty of fresh fruits and vegetables can greatly decrease your risk.
Types Of Lung Cancer
Lung cancers are broken down into two major types, small cell lung cancer and nonsmall cell lung cancer. The difference between the two types involves where they originate, how fast they grow, and how they are best treated.
Small cell lung cancers comprise roughly 15% of all lung cancer cases (ACS, 2010). This type of lung cancer originates in an inner layer of the walls of the bronchi called the bronchial submucosa, and grows aggressively (in comparison with nonsmall cell lung cancers), quickly spreading into surrounding tissues, and ultimately, through the body. Though the growth of this cancer is rapid, there are few or no clues that anything is particularly amiss. Symptoms are generally not noticeable until the cancer has spread into other parts of the body. Because of their rapid growth pace and tendency to metastasize, small cell cancers are described with only two stages (limited – when spread is contained to the localized area of the lung and immediate surrounding tissues, and extensive – when the cancer has spread throughout the body). By the time patients present for treatment, small cell lung cancers have generally reached their extensive stage. Treatment generally takes the form of a combined chemotherapy and radiation therapy approach.
Non-small cell lung cancers comprise about 85% of all lung cancers and can be broken down into three subtypes; squamous cell carcinoma, adenocarcinoma, and large cell lung cancer (ACS, 2010). Treatment of these types of cancer typically includes a combination of surgery, chemotherapy and radiation therapy.
- Squamous cell carcinoma most often begins in the larger sections of the bronchi. It progresses slowest of all of the lung cancers.
- Adenocarcinomas have the fastest growing incidence of any type of lung cancer in the United States, reported with frequency in both smokers and persons who never smoked. They typically occur at the periphery of the lungs, and grow more aggressively than squamous cell forms of lung cancer.
- As the name suggests, large cell lung cancers form as clusters of large undifferentiated cells. Like ademocarcinomas, they tend to occur at the periphery of the lung, growing and spreading more aggressively than squamous cell forms of lung cancer.
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Lung cancer is a carcinoma that develops in the epithelial cells that form the interior lining to the lungs. The airways get the most exposure to inhaled pollutants, thus most people who get lung cancer are smokers. Lung cancer is not just one disease. There are many types of cancer that form in the lungs most of which you can only see through a microscope.
The most common cancer of the lungs is epidermoid. It is also known as squamous carcinoma because its cells look like a flat surface called a squamous cell. This cancer produces keratin, a substance found in skin and hair, which can be seen in a tumor. Squamous carcinoma is more common in smokers because it develops in the bronchi and spreads by invading local tissues, than to the lymph nodes and into the blood.
Large - cell carcinoma is a tumor that is fairly larger than other types. They don"t form keratin but they are common in smokers. They develop in the central or peripheral part of the lungs and the lymph glands.
Small cell carcinoma tumors are small and fragile. They are divided into groups by their shapes. The term "oat cell carcinoma" is used to develop in smokers and usually in the central part of the lung. They spread by the lymph glands and into the blood stream early. This type of tumors can only be seen through an electron microscope on high magnification. A rare type of lung cancer, which develops from hormone producing cells are carcinoid tumors. They have a much less malignant course than small cell carcinoma.
Lung cancer has been blamed on many factors but the most important is smoking. Smoking is the main cause of lung cancer. The more often and longer a person smokes increases there chances of lung cancer. Cigarrettes are supposed to releive stress and depression, thirst and hunger. In reality they are only killing inside of you although you cant see it. Many people who have smoked for years figure the damage is already done so why quit. The risk of death from lung cancer is related to the number of smoked ciggarettes per day and the age the smoker started. There is only a small risk for non smokers to develop lung cancer. Although there is a risk of poeple who are around a lot of smokers from second hand smoke.
It has been suggested taht the association between smoking and lung cancer is genetiv rather than casual. Genetic influences may determine which smokers are more likely to develope lung cancer. Only a minority of smokers who develop lung cancer do so by inheritance. That alone makes them more suseptable to the cancer causing agents in cigarette smoke.
Another cause of lung cancer is air pollition. Coal smoke appears to be increased in the risk of lung cancer but it"s effects are small compared to that of smoking. Poeple who work in industries and that are exposed to asbestos dust, nickel, arsenic, radioactive materials, mustard gas and the products of coal and distillation are at an increased rate of developing cancer of the lungs.
Most causes of cancer are only discovered when someone goes to there doctor feeling ill. Some tumors can be found on a routine chest x - ray. Lung cancer in the early stage no signs of ill effects at all. As the tumor grows it starts to cause symptoms due to it"s invasion into the tissues of the lung and airways. Lung cancer is often suspected when someone coughs up blood or complains of a hacking cough that continues to get worse. What the lung is trying to do is get rid of the object that is lodged in the airway. I fhte tumor grows the patient will expeiriance chest pain anjd difficulty breathing. Often these symptoms are caused by a chest infection which doesn"t respond to the usual antibiotics and it is only when a chest x - ray is taken and the cancer is found.
About two in every 5 patients have a cough as their first symptom. Anyonw who has lung cancer develops a cough somewhere along the way. Anyone who has a continous cough should see there doctor. It is not good to just call it a "smokers cough". Cancer invading the mucus airways irritates the nerves which starts a cough and that cough usually doesn"t remove the cancer so the cough becomes persistant. Any bleeding is very irritating to the lining of the bronchi and will cause blood to be coughed up. Coughing may occur if the irritation is severe and cannot be cleared. This can be servere enough to crack a rib and damage small blood vessels in the lungs. The cough caused by lung cancer is often most noticable at night and first thing in the morning.
The second most common symptom occuring in about 1 in 5, is a chest infection. This is due to an inflammation of the lining over the lungs. A chest infection may cause chills, fever, night sweats, loss of appetite and weight. Infections may not respond to antibiotics and if complete blockage occurs the patient may expieriance shortness breathe, cough and a fever may rapidly develop. Symptoms and their serverity depend on how much of the lung is affected.
There are many differabt types of treatment for lung cancer and a number of them can be used topgether. Anyone with lung cancaer is of course hoping for a cure. Every effort is made to identify those who can be cured for treatments. One kind of treatment is surgery. Surgery is often the best and only chance of cure so it is important that patients are not denied the possibility. Once the diagnosis of lung cancer is made patients will be checked to see if there tumores can be removed. The first step is to see on a chest x - ray if it is small enough to operate on. A patient may benifit from an operation if the cancer hasn"t spread outside the chest or too the other lung. Because a lung may need to be removed it is important to make sure the other lung will be able to work after the operation. Patients will have a series of test called "lung fuction studies" done to test their lungs and there breathing capacity. Unfortunatly moast patients can not be operated on because some who have an operable tumor are too sick or their lungs will not work properly after the operation. Treatment for inoperable tumors will be choosen by the patient and may include radiotherapy, drug treatment as well as the treatment of specific symptoms.
Radiotherapy is the use of x - rays and other types of so called "ionizing radiation" to treat cancer. High Doses of radiation damage the mechanisms that control the division of cells and cancers are often more senssative to its effect than surrounding tissues. The odse of radiation that can be given is limited by the amount of damge done to normal tissues. Because of this it is not possible to give enough treatment to kill all the cancer cells. It is safer and more effective to divide the treatment up. It is usually given 4 - 5 times a week. Most treatments courses take around 3 - 6 weeks to complete. When treatment is given the patient is left alone and only the radiographer is able to see them through a special window and can talk through an intercom system. Each treatment, which is given through a large machine, only takes a few minutes. After the treatment patient will have side effects such as reddening and soreness, tiredness, pain and swelling, naseau and loss of appetite, sleepiness, loss of memory and cough. Radiotherapy followed by surgery is usually the best treatment for patients with cancer confined high up in the lungs.
Another type of treatment for lung cancer is chemotherapy. This is the use of drugs to trat cancer, While drugs ca be used to cure some cancer, only a minority of patients with lung cancer are responsive to drug treatment. There are a number of drugs which are able to shrink tumors at least by half. Although single - drug chemotherapy does cause tumor shrinkage it rarely prolongs life. Several drugs are being used in combninations now. Patients who are feeling very sick, who have lost a lot of weight or who have had prior radiotherapy are likely to respond pooly to drug therapy.
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