What Are the Different Types of Lung Cancer and How Do They Differ - Term Paper Example

Running head: LUNG CANCER Lung Cancer: What are the different types of lung cancer and how do they differ? April 3, 2009 Lung Cancer: What are the different types of lung cancer and how do they differ? Human body is made up of millions of cells which divide and reproduce so that the body can grow as well as repair itself in case of injury. This division and reproduction is controlled naturally by the human body. When the human body receives a cut or an injury, the cells in the skin get a natural signal prompting them to divide to form new cells which fill the injured area and heal the wound (Williams, 1992, p.3). As soon as the healing process is complete, the cells receive another message that informs them that it is time to stop dividing. Occasionally this natural mechanism of controlling cell division may become impaired in that a cell may receive the signal to begin division but not the one to stop or the cell may receive the signal to stop but may not be able to respond to it (Williams, 1992, p.3). In such a condition, the cell may be permanently or indefinitely switched on and may continue to divide indefinitely. The cells formed by the division of defective cells may themselves be defective and may also continue dividing unchecked. These cells may eventually form a cancer. They may grow randomly at the site of origin initially and eventually may spread to other parts of the body by invading the local tissues through blood vessels or the lymphatic system (Williams, 1992, p.3). Cells undergo different stages of change before they totally develop into a malignant tumor. Cells that have grown abnormal but are not yet malignant or cancerous are said to be in the pre-malignant or precancerous stage. Such cells may not always develop further to become cancerous. Cancer of the lung is commonly seen in developed, affluent countries. The risk of developing lung cancer is higher in industrialized countries than in developing countries. People living in the United Kingdom are known to have the highest risk of developing lung cancer, while this risk is lowest for people living Nigeria (Williams, 1992, p.10). Similarly, the risk is higher for men than for women. Smoking is a very significant risk factor for lung cancer as also is exposure to carcinogens like asbestos. Other causes of lung cancer include passive smoking, tobacco use, air pollution and lung diseases such as chronic obstructive lung disease and tuberculosis (Stoppler, 2009, p.2). Persistent cough, a change in the pattern of existing cough, shortness of breath, phlegm production, painful breathing or coughing, loss of appetite, fatigue and weight loss are the general symptoms of lung cancer (Cancer Research UK, 2002a). Change in quality of voice, difficulty swallowing, clubbing of fingers, swelling of the face due to superior vena cava obstruction, swelling of the neck from enlarged lymph nodes, pain under the ribs on the right side from the liver and shortness of breath due to pleural effusion are some of the less common symptoms. Some of the other rare symptoms of lung cancer include numbness of fingers and toes; muscle weakness, drowsiness, general weakness, dizziness or confusion; swelling of breasts in men and thrombosis (Cancer Research UK, 2002a). Types of Lung Cancer There are basically two kinds of cancer, namely primary and secondary lung cancer. Primary lung cancer is cancer that has primarily started in the lung. Secondary lung cancer is cancer that has spread to the lungs from somewhere else in the body. Secondary lung cancer is the type of cancer that originates in other regions of the body and eventually spreads to the lungs. Examples are breast cancer and bowel cancer (Cancer Research UK, 2002c). Management option for any type of lung cancer is decided based on its stage of development at the time of treatment. I. Primary Lung Cancer Primary lung cancer is cancer that begins in the lung. Primary lung cancer can be mainly categorized into two, namely, small cell lung cancer and non-small cell lung cancer. A. Small Cell Lung Cancer About 20 out of every 100 lung cancers diagnosed are found to be small cell lung cancers. Small cell lung cancer is made up of small cancer cells that are almost filled by the nucleus. These cells are also called oat cells. Though the cells are small, they multiply rapidly to form large tumors that can spread throughout the body (“Lung cancer 101,” n.d.). These tumors are believed to develop from a special type of hormone-producing cells, and the cancer cells show these hormone-producing special structures when viewed under the high magnification of an electron microscope (Williams, 1992, p.8).This type of cancer usually develops in the central areas of the lung. Smoking is the major cause of small cell lung cancer which is seldom seen in non-smokers. As small cell lung cancer spreads early, chemotherapy is suggested to be a more appropriate treatment than surgery in most of the cases. This is because, though surgery may remove the cancer locally, it may not treat the cells that might have already spread to other parts of the body prior to surgery (Cancer Research UK, 2002e). Another treatment that is considered suitable for small cell lung cancer is radiotherapy. 1. Stages of disease The development of small cell lung cancer is generally considered to be in two stages – the limited stage and the extensive stage. The treatment approach for small cell lung cancer is decided depending on the stage of development of the disease. In the limited stage of small cell lung cancer, the treatment approach is usually a combination of chemotherapy and chest radiation (Mayo Foundation, 2001). Oftentimes, a brain radiation treatment is also given to the patient in order to prevent the cancer from spreading to the brain, which is not an uncommon eventuality in small cell lung cancers. Chemotherapy is the most important treatment approach in the extensive stage of small cell lung cancer. In addition to chemotherapy, radiation treatment is given to local areas that may have pain or other complications (Mayo Foundation, 2001). B. Non-Small Cell Lung Cancer Non-small cell lung cancer is categorized into three, namely, squamous cell carcinoma, adenocarcinoma and large cell carcinoma. All these types of cancer cells behave in a similar way and occasionally it becomes difficult to diagnose the type of cancer that a patient has. If the cells are largely undeveloped in the biopsy, such cells are referred to as undifferentiated cells. However, the treatment options are the same for all types of non-small cell lung cancer (Cancer Research UK, 2002c). 1. Squamous cell lung cancer Squamous cell lung cancer is one of the most common types of lung cancer. This type of cancer develops from the cells that line the airways. This is mostly found near the center of the lung in the lining of the large bronchi or in the periphery of the lung (Mayo Foundation, 2001). This type of cancer occurs mostly due to smoking and is commonly seen in men (“Lung cancer 101,” n.d.). The cells resemble flat-surfaced cells called squamous cells. The tumor cells produce keratin, which is usually found in skin and hair. The tumor is usually associated with extensive dysplastic changes, i.e., abnormal tissue development, and metaplasia, i.e., abnormal transformation of one kind of adult, differentiated tissue into another (Williams, 1992, p.7). 2. Adenocarcinoma Adenocarcinoma also develops from the cells that line the airways, however, this develops from the particular type of cell that produces mucus. This is usually found in the outer regions of the lungs and has a tendency to spread to the lymph glands in the lung and to the bloodstream and other organs (Mayo Foundation, 2001). There has been found to be increasing incidence of adenocarcinoma in the recent times. This is the most common type of lung cancer seen in women and nonsmokers (“Lung cancer 101,” n.d.). The tumor, which is derived from glandular tissue, sometimes tends to form new glands (Williams, 1992, p.7). 3. Bronchoalveolar Carcinoma Bronchoalveolar carcinoma is a subtype of adenocarcinoma. This is a rare type of lung cancer which develops near the air sacs of the lungs. Bronchoalveolar carcinoma responds best to targeted therapies which are treatment approaches that target and treat only the cancer cells, without damaging the normal cells (“Lung cancer 101,” n.d.). 4. Large Cell Carcinoma In large cell lung cancer, unlike in small cell lung cancer, the cells when viewed under a microscope look large and rounded. They neither tend to form identifiable structures, like glands, nor do they produce keratin (Williams, 1992, p.7). These cancer cells grow quickly. Large cell carcinoma also occurs mostly in the periphery of the lung. 5. Stages of Disease Cancer develops through different stages and the treatment options for non-small cell lung cancer are decided based on the stage of the cancer to be treated. At Stage 0, the cancer is limited to the surface of the bronchus, so surgical resection can be a reasonable treatment option. Another option is photodynamic therapy whereby laser is used to destroy cancer cells (Mayo Foundation, 2001). At Stages I and II, surgery is opted whenever surgery is appropriate. When surgery is not appropriate, a possible treatment option is radiation with or without chemotherapy. At limited Stage IIIA disease, surgery may be considered with or without preoperative chemotherapy (Mayo Foundation, 2001). If surgery is impossible, chest radiation is combined with chemotherapy. Surgery is not usually an option for Stage IIIB tumors. At Stage IV, surgery is not considered an option. Chemotherapy is the main form of treatment along with radiation to the chest and to other areas that has pain or other problems (Mayo Foundation, 2001). II. Secondary Lung Cancer Secondary lung cancer is cancer that has originated in other regions of the body and then spreads to the lungs. Examples are breast cancer and bowel cancer (Cancer Research UK, 2002c). It is important to know the origin of the cancer, as the choice of cancer treatment depends on where the cancer originated. For example, if the cancer cells have spread from breast to the lung, the cells are not lung cancer cells but breast cancer cells. Hence, option for treatment should be breast cancer treatment. Similarly, cancer that has spread from the bowel to the lung is best treated with bowel cancer treatments (Cancer Research UK, 2002c). III. Mesothelioma Mesothelioma is a rare type of lung cancer that affects the covering of the lung or the pleura. This type of cancer is usually caused by exposure to asbestos. This is a cancer of the mesothelial cells that form a lining on the outer surface of the internal body organs, called the mesothelium (Cancer Research UK, 2002d). It can develop in the tissues covering the abdomen as well as the lung. These tumors tend to cause fluid accumulation between the lung and the chest wall, known as pleural effusion. Mesothelioma develops through different stages where Stage 1 is the earliest stage and Stage 4 is the most advanced stage, according to the TNM staging system. At Stage 1a, mesothelioma affects the outer layer of the pleura around the chest wall on one side only and may have grown in the pleural tissue covering the diaphragm (Cancer Research UK, 2002b). At Stage 1b, it has spread to the inner pleural layer, but still remains on one side of the chest only. At Stage 2, it has spread to both layers of pleura on one side of the body, forming a tumor mass on the pleural tissue around the lungs, or spreading to the diaphragm muscle or the lung tissue. At Stage 3, the disease has spread to the chest wall or the pericardium or to the lymph nodes on the same side of the chest. At Stage 4, it has spread extensively to different parts of the body and hence is not removable by surgery (Cancer Research UK, 2002b). Conclusion Growth of cells in the human body by division and reproduction is normally controlled by a natural mechanism of the human body. Sometimes this natural mechanism becomes defective in a cell so that there is continuous and indefinite multiplication of cells. The new cells produced in this way also tend to be defective. Lung cancer is the uncontrolled and indefinite growth of abnormal cells in the lung. These abnormal cells may eventually form a cancer. Lung cancer is one of the most common cancers, which is presently seen mostly in men, though women with lung cancer have also started increasing in number. The majority of the people who get lung cancer are smokers. Adenocarcinoma is the most commonly seen lung cancer in nonsmokers and women. Persistent cough, a change in the pattern of existing cough, shortness of breath, phlegm production, painful breathing or coughing, loss of appetite, fatigue and weight loss are the general symptoms of lung cancer. Lung cancer can easily go undetected as its symptoms, like a persistent cough, may be easily believed to be due to other diseases, like a cold or bronchitis. Lung cancer can be basically divided into primary and secondary lung cancer. Primary lung cancer is divided into small cell and non-small cell lung cancer, which is again divided into squamous cell carcinoma, adenocarcinoma and large cell carcinoma. Mesothelioma is another rare type of tumor that affects the pleura. Smoking cessation and avoiding exposure to carcinogens like asbestos can help prevent lung cancer to some extent. Other measures that can help reduce the risk of lung cancer are avoiding passive smoking and quitting or avoiding usage of tobacco which is considered to be a major risk factor for lung cancer. References Cancer Research UK (2002a). Lung cancer symptoms. Retrieved April 1, 2009. from http://www.cancerhelp.org.uk/help/default.asp?page=2964 Cancer Research UK (2002b). The stages of mesothelioma. Retrieved April 2, 2009, from http://www.cancerhelp.org.uk/help/default.asp?page=4465 Cancer Research UK (2002c). Types of lung cancer. Retrieved April 2, 2009, from http://www.cancerhelp.org.uk/help/default.asp?page=2965#secondary Cancer Research UK (2002d). What mesothelioma is. Retrieved April 2, 2009, from http://www.cancerhelp.org.uk/help/default.asp?page=4393 Cancer Research UK (2002e). Which treatment for lung cancer? Retrieved April 2, 2009, from http://www.cancerhelp.org.uk/help/default.asp?page=2971 Lung cancer 101: Types of lung cancer (n.d.). Retrieved April 2, 2009, from http://www.lungcancer.org/reading/types.php Mayo Foundation for Medical Education and Research (2001). Lung cancer. Retrieved April 2, 2009, from http://www.mayoclinic.org/lung-cancer/types.html Stoppler, M.C. (2009). Lung cancer causes. Retrieved April 1, 2009, from http://www.emedicinehealth.com/lung_cancer/page2_em.htm Williams, C. (1992). What is lung cancer? In Lung cancer: the facts (1). Retrieved April 1, 2009, from http://books.google.co.in/books?id=qNc5w4qCUNAC&pg=PA3&dq=lung+cancer+types#PPA3,M1 Read More