Cancer is the condition of abnormal growth of body cells. It is well defined by the uncontrolled growth of the cells that makes up the various body tissues. A cancerous growth is capable of spreading to various tissues and organs in the process known as metastasis. Cancer is usually caused by various substances or conditions that include carcinogens, radiations or viral infections that cause DNA mutations.
The cancer of the lungs is usually recognized by cells of the lungs tissue growing in an uncontrolled condition. This condition usually originates from the epithelial cells of the lung's tissue in a process known as primary cancer of the lung. Lung cancer is caused by a number of factors which range from tobacco smoking, genetic mutation of the lung tissue cells, air pollution, asbestos and the inhalation of the radon gas. There are two main types of lung cancer; the small-cell lung cancer and non-small-cell cancer. Lung cancer symptoms include coughing of blood breath shortness and weight loss. Lung cancer is usually diagnosed through chest radiographs and the process of computed tomography (CTscan) as well as tissue cell biopsy. Lung cancer is treatable using chemotherapy, radiotherapy, and surgical processes.
Causes of lung cancer
More than 60 of known carcinogens are contained in the tobacco smoke. The carcinogens include radioisotopes in the decay sequence of radon which is benzopyrene and nitrosamine. Nicotine also has the effect of depressing the immunity of tissues to malignant growths. Smoking accounts for the highest number of lung cancer deaths being rated at 91% in men and 71% in women. Lung cancer developing chances increases with the rate a person is smoking at. A person who has stopped to smoke for instance is likely is likely to decrease lung tissue damage and facilitate the removal of contaminant particles. It is, however, likely that a nonsmoker can acquire lung cancer from passive smoking where smoke from a smoking person is inhaled.
Viruses alter the cell cycle processes and inhibit the apoptosis process of the lung cells leading to cancerous growth in the lung tissue. Some of these viruses include the cytomegalovirus, the human papillomavirus, the BK virus JC virus and the simian virus 40.
Radon is a gas generated from the radioactive radium breakdown. Radium is a decay product of uranium. The radiation from this gas causes the ionization of genetic material resulting in cancer.
Particulate matter in the air
Some particles in the air have the ability to penetrate lung tissues and alter their functions causing mutations that result in the lung cancer condition. High concentration of particles in the air increases the risk of lung cancer.
Asbestos and tobacco smoking have a synergistic effect that leads to cancer of the lungs. Asbestos contributes to a significant percentage lung cancer disease which occurs through t mutations in the lung cells.
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Signs and symptoms lung cancer
Lung cancer may be suggested by a number of symptoms which mostly depend on the type of lung cancer. When cancer grows and obstructs the airway it results in difficulties during breathing. Secretions' accumulates on the blocked air channels acting as a predisposing condition to the pneumonia disease (Schiller, 2009). The cancerous tissue causes an increase the supply of blood making the area fragile which results in breeding. Tumors may pear on the apex regions of the lungs. The symptoms to observe include dyspnea, hemoptysis chronic coughing, wheezing, chest pain, weight loss, dysphonia and difficult .in swallowing. There are also some nonspecific symptoms such as bone pain, fever and weight loss are general and may be taken for other illnesses.
Parthenogenesis of Lung Cancer
Lung cancer starts by activating oncogenes which are the genes that reduce the human immunity to cancer they increase the susceptibility to cancer (Schiller, 2009). Oncogenes arise when proto-oncogenes are exposed to specific carcinogens responsible for lung cancer.
For lung cancer, mutations occur in k-ras-proto-oncogenes that are responsible for 30% lung adenocarcinomas. When mutations and gene amplification occur chromosomal damage causes the loss of heterozygosity resulting the tumor suppressor gene to becoming inactivated. Small-cell lung carcinoma occurs when damages occur to 3p, 5q, 13q and17, p chromosomes this because the p53 which is a tumor suppressor gene is affected when changes occur in the 17p chromosome in which the gene is located (Schiller, 2009). People with genetic polymorphism develop lung cancer when they are subjected to carcinogens. This is because the polymorphism affects occurs in genes coding for interleukin-1 and cytochrome p450. The polymorphism also affects also affects the genes coding apoptosis promoters and DNA repair molecules leading to cancerous growth in lung cells and tissues.
Diagnosis of Lung Cancer
To diagnose lung cancer, a patient is first subjected to chest radiograph when the symptoms give much those of along cancer patient. A CT scan or bronchoscopy is also carried out for cancer detection especially on the patient whose radiographic examination is negative but lung cancer suspicion is high. A radiograph test usually reveals the widening of the mediastinum, an obvious mass, atelectasis and pleural effusions. Sputum cytological tests involving cell atypia is checked for early cancer detection as another method of lung cancer diagnosis. Definitive lung cancer diagnosis, however, is based on the microscopic examination of the suspected tissue.
Lung Cancer Classification
Classification of lung cancer is done according to the histological type. The classification is important for the management and prognosis of the disease. Carcinomas are the majority of lung cancers. These are the malignancies arising from the epithelial cells.
Nonsmall-cell and the small-cell lung carcinoma are the two prevalent categories of lung cancer. Occurring on the outside of the lungs the non-small-cell type is the most prevalent lung cancer type. Cancer metastasizes from a specific cell and can hence be traced back to the point of origin. It is thus also known as the primary lung cancer. The cancer is further grouped to the squamous cell lung carcinoma the adenocarcinoma and the large-cell lung carcinoma.
Squamous cell cancer originates from a central bronchus. It is characterized by a hollow cavity and necrosis at the tumor center. Adenocarcinoma usually is found at the peripheral of lung tissue. This type occurs mainly from smoking but is also the most common form of lung cancer among the non-smokers. Bronchioloalveolar cancer is the most common type of cancer among the female non-smokers.
Small cell lung cancer occurs in the larger air tracks and is quite large with a rapid growth. The cells in this type of cancer are filled with neurosecretory granules which are vesicles that contain neuroendocrine hormone and hence the endocrine paraneoplastic syndrome nature of the tumor. The tumor metastasizes immediately upon presentation. Small cell lung cancer is strongly associated with smoking.
Lung Cancer Staging
This the determination of the lung cancer spread from its original source. The process of lung cancer staging is important in the treatment and the prognosis of cancer. The lung cancer process is usually done before curative therapy is carried out. The process entails a number of tests. The tests include the physical examination of the cancerous growth laboratory tests, the cancerous imaging studies and the tissue biopsies of the cancerous growth. For nonsmall cell lung cancer, the staging is usually from IA-IV (best to worst prognosis). Small cell lung cancer is classified from limited to the extensive stage.
Non-small-cell-lung-cancer and small-cell-lung-cancer are evaluated as clinical and pathological staging (Schiller, 2009). Clinical staging involves evaluation prior to definitive surgery and is based on the results of physical examination, imaging studies and laboratory findings (Hansen, 2010). Pathological staging is usually evaluated as intro or post- operatively and is based on clinical and surgical findings (Society, 2007). Small-cell lung cancer in two systems; the limited stage that is usually confined to the area of origin of cancer in the chest and the extensive stage for cancer that is spread the region of the chest and to other body parts.
Lung Cancer Treatment
Lung cancer involves various methods ranging from surgical removal, radiation therapy, chemotherapy as well as a combination of all the treatments. The suitable treatment method depends on the extent and location of the lung tumor and the health status of a patient. A lung cancer treatment may be palliative or curative. Curative treatment is usually intended to eradicate or remove cancer while a palliative one involves measures being taken to reduce lung cancer suffering and pain. An adjuvant is taken for the purpose of effecting primary therapy. Such an adjuvant is chemotherapy that is administered after surgical tumor removal as an attempt for an elimination of tumor cell that may have remained after tumor removal surgery.
Treatment through Surgery
This type of tumor removal is performed in the initial stages of lung cancer when the spread of the cancer is not beyond the lungs. The success of surgery as a means of tumor removal is dependent on whether cancer has spread beyond the lung region or not. When cancer has spread beyond the lungs surgery may not be an effective means of removal as the cancerous cells will continue to undergo metastasis. Only about 30% of cancer can be removed surgically because lung cancer surgery is not possible if the patient has other serious health problems such as heart disease which is a limitation to an operation survival. Surgery as means of lung cancer treatment is, however, common in non-small cell lung cancer than it is in the small-cell lung cancer.
Surgery lung cancer treatment requires that the patient is subjected to anesthesia, be hospitalized and undergo a follow-up care for sometimes The process of lung cancer surgery involves opening the chest wall through an insertion into the chest wall. A portion of the lung or the entire lobe is removed and the tumor on the lung tissue removed. The operations may be followed by shortness of breath, difficulty in breathing and weakness. The surgery may have the risk of bleeding complications and general anesthesia complication.
Treatment by Radiation
This is the use of high-energy X-rays or some form of other radiations to destroy cancerous cells in a lung cancer (Schiller, 2009). This treatment is applied to both palliative and curative management of lung cancer, however, lower levels of radiations are used for palliative management than in curative management. The radiations can also be in form of adjuvant therapy together with chemotherapy or surgery. Radiations can be delivered by a machine externally where the radiations are directed towards cancer. Internally a radioactive substance in sealed containers is placed at the tumor in the lungs.
Radiation treatment is usually are applied when the tumor has spread to other areas other than the cancer tissue hence surgical operations are difficult to be carried out. The procedure is also adopted in cases where the patient is suffering from other complications and illnesses. The radiation treatment works by limiting the growth of the tumor. External therapy is mainly given to lung cancer patient on an outpatient basis while internal treatment with radiations calls for hospitalization of the lung cancer patient.
For an external radiation treatment, precise measurements are taken using computers and CT scans to make a simulation map on the exact location of a radiation treatment. The treatment is then carried out and usually takes four to five days in a week for some weeks.
Radiation therapy does not carry with it major risks as it is for the case of surgery but its side effects include fatigue and lack the feeling of lack of energy. Cases of bleeding, nausea, vomiting and diarrhea may be experienced by patients who have been subjected to radiation therapy treatment. Cases of skin irritation may also be experienced in the area of radiation treatment but the feeling fades with time after the treatment is over.
Treatment by Chemotherapy
This method of treatment is applicable to both non-small-cell-lung cancer and small-cell-lung cancer management (Hansen H. H., 2010). The treatment entails the administration of a drug to stop cancer cell growth. The drug may kill the cancerous cells or inhibit the division of the cancerous cells. The treatment may be as an adjuvant given alone top surgical therapy or may be a combination of radiotherapy. Chemotherapeutic drugs which are Platinum-based are taken as the most effective treatments for lung cancer. Since small-cell lung cancers are usually widespread in the body, chemotherapy has been adopted as the most suitable treatment for them. Chemotherapy treatment is effectively able of increasing the survival time of lung cancer patient to about four to fivefold.
The administration of chemotherapy drugs is through ingestion in form of pills, intravenous infusion or it can be taken in both forms. Chemotherapy treatment is mainly administered to outpatient of lung cancer disease. The drugs are given out in cycles of treatments in a period which ranges from weeks to months which are usually occasioned by breaks within the cycles.
One of the greatest risks of chemotherapy is their ability to kill even the dividing normal body cells. This effect causes a lot of side effects and increases the susceptibility of the body to infections and also failures of blood to clot. Chemotherapy drugs may also lead to vomiting , however hair loss, nausea, diarrhea and mouth sores although the side effects o these drugs varies with the amount of dose administered and the individual taking the drug. , however, edications that have been developed to treat or prevent chemotherapy side effects although the side effects of these drugs ease as the patient undergoes recovery.
Prophylactic Brain Radiation
Small cell lung cancer usually spreads to the brain and radiation therapy is administered to the head to reduce any chances of the cancer spread to the brain. The effect of radiation therapy subjected to the brain includes nausea, memory loss and fatigue.
Treatment by Targeted Therapy
When non-small cell lung cancer is not responding to chemotherapy the targeted therapy treatment method is usually adopted. The treatment involves the use of erlotinib and gefitinib targeted drugs. The drugs have the ability to be more specific on targeting cancer cells and causing fewer damages to the normal lung cells. These drugs work by targeting the epidermal growth factor receptor protein that is necessary for cell division. Their specificity is due to the abnormally high levels of this protein on the surfaces of cancerous cells which includes the non-small cell lung cancer.
Other forms of targeted cancer treatment include administration of antiangiogensis drugs. These drugs work by blocking the development of new blood vessels in a cancerous growth leading to the cancer cell death due to lack oxygen which is usually carried by these blood vessels.
Treatment by Photodynamic Therapy
A photosynthesizing agent like phorphyrin which is a natural substance found in the body is injected into the patient's blood stream a few hours before along cancer patient is taken in for cancer surgery. The cancer cells rapidly take up the agent and the physician then applies a wavelength of light to the cancerous tissues. A toxin that destroys the tumor cells is produced when the light activates the photosensitizing agent. The treatment is capable of precisely targeting and destroying the cancerous cells and is less invasive than surgery and can be repeatedly carried out at the same location and therefore capable of effectively eliminating the cancerous growth in the lungs. The mode of treatment is however limited in that it is only possible to eliminate lung cancer that can be reachable to a light wave.
Treatment by Radiofrequency Ablation
This is a method of treating lung cancer at its early stages. The method involves using a CT scan to locate a cancerous growth and inserting a needle into the tumor. Radiofrequency energy is subjected to the tissue where it produces heat in the tissue therefore destroying the tumor. The treatment also causes the closing of small blood vessels that supplies the cancerous tissue with blood leading to their death.
Prognosis of Lung Cancer
Lung cancer is the determination of cancer survival chance after attack or the possibility of the cancer being cured. Lung cancer prognosis is usually dependant on; the health status of the affected patient, the symptoms of the lung cancer that the patient is showing and the type of lung cancer that the patient is suffering from.
Small-cell lung cancer is the cancer with the most aggressive growth among the lung cancer categories. This type of lung cancer has a survival time of between two to four months of survival time if left untreated. This disease type however has very high response to radiation treatment and chemotherapy. Due to the rapid ability of small-cell lung cancer spreading, surgical removal and radiations that are localized are not effective in the treatment of this type of lung cancer. Chemotherapy increases the survival time by four to five folds when administered alone or together with other treatment methods.
For non-small cell lung cancer, the most important determinant is the extent of the cancerous spread during the time of diagnosis. The cancer is very difficult to eliminate at advanced stage when it has spread to other tissues. The cancer can be completely removed using surgical operation during the early stages when the cancer has not yet spread to a number of other tissues. Radiation treatment only produces cure to a small number of patients with non-small cell lung cancer and only causes a relief to patient's symptoms. Chemotherapy only gives some modest improvements but has a poor overall survival.
The overall lung cancer prognosis is poor when compared with other form of cancers with survival rates being than those of other cancers. The overall rate of lung cancer survival ranges from 15% -20%.
Lung Cancer Prevention
Lung cancer can most effectively be prevented by stopping cigarette smoking among smokers and eliminating the exposure tobacco smoke. Nicotine gum and sprays can help be used to help people quit smoking. Home radon test kit can be used to detect increased levels of tobacco smoke in homes and hence the appropriate measures taken. Methods that allow early detection of lung cancer such as CT scans can be adopted to prevent cancer spread at early stages. Endotoxins are also used in the prevention and control of the spread of lung cancer. This comes from a realization that most of the people that have in the past been exposed to endotoxins have in great numbers failed to get infected with lung cancer, even though many a times they are cigarette smokers or users of other nicotine based drugs.