Lung cancer

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Lung Cancer
Introduction
Cancer refers to the uncontrolled segregation of cells of abnormal cells described as the cancerous growth of cells. Lung cancer is a malignant tumor that develops in different parts of the lungs and its tissues. It is among the most popular and dangerous forms of cancer and contributes to more cancer death than any other type of cancer. The growth of tissues can lead to tumors that extend beyond the lungs occurs in a process known as metastasis; where the malignant tumors grow aggressively from their point of origin and can even move to the lymphatic system and the bloodstream. The lung is a vital organ in the human body, the nature of lung cancer makes it very dangerous and also difficult to cure.
Even though lung carcinoma can spread to other body organs, specific organs are usually affected first by the metastasis like the liver, brain, adrenal glands, and bones. The lung can also be affected by the spread of malignant tumors from other body organs and tissues. The majority of people diagnosed with lung cancer are tobacco smokers and mostly later in life with statistics showing an average age of 65-71. It is critical that each is sensitized on the various types of cancer and most importantly lung cancer; this paper presents an elaborate analysis of lung cancer explaining its history, epidemiology, etiology, pathophysiology, pathology, symptoms, and treatment.
Historical Background of Lung Cancer.
Lung cancer was not known by many before people started smoking a cigarette; it was recognized as a disease in 1761.

Various attributes of lung cancer were described further in 1810. An 1878 autopsy identified indicated that malignant lung cancer made up 1% of all various forms of cancer and the figure increased to 10-15% by the start of the 1900s making it the second most dangerous form of cancer at that time after stomach cancer. A case report analysis in 1912 only identified 374 cases of lung cancer all over the world. However, an autopsy review done in 1952 indicated an increase in lung cancer incidence from 0.3% in 1852 to 5.66% the same year. Smoking was first linked to lung cancer in 1929 by a German physician (Witschi, N.p).
The connection between lung cancer and radon gas was first established among silver miners working in the Ore Mountains; since these mines were mainly composed of Uranium which contains radon and radium gas. Miners in these mines developed minor lung infections, which was eventually identified as lung cancer around the 1850s. The mining continues due to high demand for uranium by the USSR. Radon was officially confirmed as a lung cancer causal agent in the 1960s. 60% to 80% of all workers in these mining areas perished from lung cancer leading to the popular name ‘death pits’ which was used to describe these minefields. Various cultures have different misconceptions about cancer in general. Egyptians believed that cancer was a curse by the Gods while Greeks, on the other hand, believed that cancer resulted from the body having excess black bile. By 2013 lung cancer accounted for 27% of all cancer death recording 159, 480 deaths. Over the years, scientists have established various factors causing lung cancer that are accepted; they include; cigarette smoking both passive and active, Asbestosis, exposure to radon gas, genetic history, and environmental factors (Witschi, N.p).
Epidemiology of Lung Cancer
Lung cancer is most common among men all over the world in both mortality and incidence. Among women, lung cancer is the third most incident type of cancer and the second regarding mortality rates after breast cancer. In 2012, lung cancer recorded a total of 1.82 million new incidences of cancer, and 1.56 million people died of lung cancer contributing to 19.4% of all cancer deaths. The highest rates of cancer were recorded in Europe, East Asia and North America. The prevalence rate in South Asia and Africa is quite lower compared to other continents. The population group with the highest lung cancer risk rate are individuals above the age of 50 with a smoking history. The mortality rate among men started declining over 20 years ago. Lung cancer in women has kept rising over the last ten years and have recently started to stabilize. In the US, the lung cancer risk is at 8% among men and 6% among women. For each 3-4 million cigarettes smoked, one person dies from lung cancer (Ridge, McErlean and Ginsberg, N.p).
The tobacco industry significantly influences the tobacco culture. Tobacco advertisements are more likely to influence young people to indulge in smoking. Passive smoking is increasingly becoming a lung cancer risk factor, and this has led to the intervention of stringent policy measures to limit the level of exposure to tobacco smoke among non-smokers. Emissions from factories, automobiles, and power plants also increase lung cancer risk. Black men and women have more lung cancer incidents in the US compared to other races. Developing countries still have low incidents of lung cancer, however; with increased smoking, the incidence rates is expected to rise over the next years especially in India and China.
Military veterans in the United States have a higher rate 20-25% of lung cancer cases due to high smoking rates. The high rates of lung cancer cases among military veterans are attributed to smoking among military men during the Second World War Furthermore, asbestos in the Korean War and Agent Orange used in the Vietnam war also contributed significantly to the lung cancer cases among veteran US military soldiers. In the UK, lung cancer is the most prevalent case of cancer; in 2011, 43,500 individuals were found to have lung cancer, and the disease directly contributed to the demise of 35,400 people in 2012 making it the most popular cause of cancer deaths. Lung adenocarcinoma rates have risen over the years since the 1960s compared to other lung cancer types; this is attributed to the introduction of cigarettes with filters. The use of filters in cigarettes eliminates large particles from tobacco smoke, thereby reducing the level of deposits. However, smokers have to inhale the smoke more deeply to gain the same amount of nicotine, thus increasing deposition of particles in small airways which leads to adenocarcinoma (Ridge, McErlean and Ginsberg, N.p).
Lung Cancer Etiology
Cancer develops as a result of epigenetic changes and DNA damage. These changes disrupt the way normal body cells function including a programmed death of cells, cell proliferation and DNA repair. Increased damages to the DNA increases the risk of cancer. The main risk factors associated with lung cancer include; smoking, Radon gas, asbestos, Air pollution, and genetics. Other factors also identified to contribute to lung cancer include; exposure to some metals, combustion products, Ionizing Radiation, toxic gasses like sulfur mustard, and crystalline dust from silica and rubber production. Out of all the risk factors, cigarette smoking is the main factor contributing to most lung cancer cases. Cigarette smoke is made up of at least 73 carcinogens which include; 1,3-butadiene, benzo[a]pyrene, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and a polonium isotope that is radioactive known as polonium-210. In developed nations, 90% of all male deaths due to lung cancer were directly linked to smoking while among women it was 70% in the year 2000. Smoking accounts for approximately 85% of all lung cancer cases. Passive smoking also causes lung cancer among non—smokers. Studies carried out in the Europe, US, and the UK has over the years shown consistent increase in lung cancer risk among passive smokers. A passive smoker living with a cigarette smoker is exposed to 20-30% risk while a person working with a smoker faces 16-19% risk of developing lung cancer (Akopyan, N.p).
Some scientists have indicated that passive smoking is more dangerous as compared to active smoking. In the United States, passive smoking contributes to the death of about 3,400 people with lung cancer. The potential effects of NNN and NNK found in tobacco smoke makes it more dangerous. NNK and NNN when metabolically activated results in deleterious mutations are genes and oncogenes that suppress tumor, this is referred to as tumor initiation. The binding of NNN and NNK to the receptor known as nicotinic acetylcholine thereby promoting the growth of tumors through deregulation and enhancement of cell survival, proliferation, invasion, and migration; and this creates an enabling microenvironment for the growth of tumors. The unique properties of NNN and NNK lead to the induction of lung cancer among individuals exposed to tobacco either passively and actively. Radon gas is odourless and colourless; it is generated during the process of breaking down radioactive radium which a decayed uranium which is found beneath the earth’s crust. Genetic materials are ionized by the radiation decay leading to mutations that at times can be cancerous. Radon is the second lung cancer risk factor after tobacco. In the United States, Radon leads to the death of up to 21, 000 people (Akopyan, N.p).
The levels of radon gas in the atmosphere vary in different locales depending on rock and soil composition beneath the earth. Lung Cancer risk increases by 8-16% for each 100 Bg/m3 radon gas one is exposed to. In the United States, one out of every 15 homes is located in areas with more than 148Bq/m3 of radon gas which is the limit recommended by in the United States. Asbestos can lead to several lung infections, lung cancer being one of them. Asbestos and tobacco smoking have the same effect on the lung cancer risk. Smokers who work with asbestos face more risk of being diagnosed with lung cancer compared all other people. Environmental pollution of the air increases has minimal effect on lung cancer risk. Sulfate emissions and fine particles possibly released in traffic exhaust fumes increase lung cancer risk. Nitrogen dioxide causes a rise in lung cancer risk by 14%. Air pollution is associated with about 1-2% of all lung cancer cases. Research has also indicated increased lung cancer risk in pollution of air indoors by burning charcoal, wood, crop residue or dung for heating or cooking. The risk affects approximately 2.4 billion individuals worldwide. Components of our genes that are inherited can also increase the risk of being diagnosed with lung cancer. Relatives of individuals with lung cancer are twice exposed to the risk compared to the rest of the population due to gene combination. The process of polymorphosis that is present on chromosomes 5, 6, and 15 contributes to lung cancer risk.
Pathology and Pathophysiology of Lung Cancer
All cancer types including lung cancers are initiated by oncogene activation or through inactivation of genes that suppress tumor. Carcinogens lead to mutation in the structure of these genes leading to cancer development. 10-30% of lung adenocarcinomas’ is directly caused by K-ras protoncogene mutation. EML4-ALK tyrosine kinase gene leads to approximately 4% of non-small-cell lung carcinomas. Epigenetic changes like modified histone tail, altered DNA methylation and regulation of microRNA can inactivate genes that suppress tumor. The epidermal growth factor (EGFR) moderates proliferation of cells, angiogenesis, apoptosis, and invasion of tumors. Amplification and mutation of EGFR occur mostly in non-small-cell lung cancer and gives the foundation of treatment done by EGFR inhibitors. The cell line of lung cancer origin has not been fully identified. However, scientists predict that it may be because of stem cells being abnormally activated. Lung cancer metastasis is dependent on the transition of epithelial cells to mesenchymal types of cells. The first stage of diagnosing lung cancer involves chest radiograph; this can reveal a visible mass, broadening of the mediastinum which indicates possible spread to lymph nodes, atelectasis, and pleural fusion. Images from CT scans are used to give more information about the extent of a disease (“Lung Cancer 101 | Lungcancer.Org” N.p).
Bronchoscopy which is a CT-guided biopsy is used for tumor sampling. In many cases, lung cancer can be seen as a single pulmonary nodule from the photographs of a cell radiograph. Lung cancer can also be unexpectedly identified on a chest radiograph done for purposes other than the diagnosis of lung cancer. The solitary pulmonary nodule can also be a sign of several other diseases including hamartomas and metastatic cancer. Identifying lung cancer can only be ascertained through histological examination of tissues and cells that are being suspected. About 40% of lung cancers are normally seen in peripheral tissues of the lung. The lung is the point of origin of all types of lung cancers, and secondary cancer types that spread to the lungs are grouped by the point of origin like, metastatic breast cancer that originates from the chest and spreads to the lungs. Primary lung cancers often spread to the bones, liver, brain, and adrenal glands. The stages of lung cancer describe its extent of spread. It affects both potential treatment and prognosis of lung cancer. For all types of lung cancer, surgical and clinical staging are the general staging evaluation types used. Clinical staging is done just before definitive surgery and is based on biopsy results and imaging studies like CT scans. Surgical staging is carried out after and before the operation. The results from surgical staging are drawn from both clinical and surgical results.
Classification and Symptoms
Several types of lung cancers exhibit different stages of development. The most common types of lung cancer are Non-small cell and Small cell lung cancers. Non-small cell lung cancer accounts for over 80% of lung cancer cases and can either be a carcinoma, large cell carcinoma, and adenocarcinoma. Small cell lung cancer is a less common than the other type of lung cancer. However, it spreads faster. Most lung cancer symptoms cannot be seen until the cancer is in its advanced stages and spread to other parts of the body. However, a few people show symptoms while the cancer is still in its early stages. The effectiveness of treatment highly depends on the stage of cancer, early stages of cancer respond better to treatment as compared to advanced cancer stages. It is important for people to take preventive measures like quitting smoking and going for screening. However, individuals who are already exposed to cancer through smoking should visit the doctor more often to increase the chances of early detection and ensure the effectiveness of treatment (“Signs And Symptoms Of Lung Cancer” N.p).
The various symptoms of lung cancer include; Persistent coughing, blood coughs or brown sputum, Chest pains that worsen when coughing, breathing deeply and laughing. Hoarseness, appetite loss and weight loss, gasping for breath, fatigue, reoccurrence of infections like pneumonia and bronchitis. When distant organs are affected by lung cancer; it may lead to symptoms like pain in the bones, changes in the nervous system leading to a headache, dizziness, seizures, and numbness and weakness of the limbs. Yellow eyes and skin which results from spread to the liver, and lumps close to body surface that emanate from spread of cancer to lymph nodes and the skin. Lung cancer shares most of these symptoms with other diseases. Therefore any indication of these symptoms should prompt medical attention from a doctor.
Some types of lung cancer lead to syndromes which are grouped based on very specific symptoms. They include; Horner syndrome which affects the top part of the lungs and sometimes extend to specific eye nerves and an area of the face. The signs and symptoms of Horner syndrome include; weak and droopy eyelid, small pupil, and Pancoast tumors. Superior vena cava syndrome is another type caused by lung cancer; it transports blood from head and arms and channels it back to the heart. It passes close to the lymph nodes and the top part of lungs at the right part of human body. Tumors located close to these parts can press the superior vena cava reversing blood flow; thereby causing swellings in the neck, arms, face, and upper chest. A reverse of blood flow in this section cause dizziness, headaches, and can affect the brain. SVC syndrome can eventually lead to death and requires immediate medical attention. Paraneoplastic syndrome is also associated with lung cancer; It is characterized hormone-like substances that enter the bloodstream and cause problems due to the advancement of lung cancer (“Signs And Symptoms Of Lung Cancer” N.p).
Treatment
Radiation, surgery, chemotherapy, and targeted treatment are some of the techniques used for lung cancer treatment. All of these treatments react differently with each.
Surgery
A majority of non-small cell cancers still in stage I and II are treated through surgery to exterminate the tumor. Surgery involves removal of a section of the lung that infested with the tumor. Surgeons can also use video-assisted thoracoscope surgery. A thoracoscope has a tiny camera and a light linked to a video monitor enabling the surgeon to view central sections of the chest.
Chemotherapy and Radiation
Individuals with non-small cell tumors can go for chemotherapy after surgery to help prevent regrowth of the tumor. Particularly for individuals with stage II and III. Stage three of lung cancer cannot be removed by surgery and chemotherapy is the most recommended form of treatment coupled with high-doses of radiation. Chemotherapy involves some drugs which include cisplatin, carboplatin, gemcitabine, docetaxel, and paclitaxel. Sometimes chemotherapy treatments may not work, and in some cases, the cancer redevelops after a while. In such cases, doctors may recommend a second type of chemotherapy.
Neoadjuvant Treatment
In this method of treatment, chemotherapy is done before the actual surgery or radiation; it can help individuals diagnosed with lung cancer by reducing the size of the tumor thus easing its removal. Furthermore, radiation can be more effective because cancer cells that are hidden can be destroyed easily. If the cancer is not reduced in size, chemotherapy should be stopped as soon as possible. Research also indicates that lung cancer patients can handle the side effects of chemotherapy done before marriage.
Targeted treatments
Targeted treatments are the most advanced forms of cancer treatment. Targeted therapies are programmed to differentiate between cancer cells and normal cells. The therapy works by protecting layers that are above the surface of cancer cells by either blocking targets or attaching to these cells. Targeted treatments are done with several types of drugs and can be combined with chemotherapy for advanced stages of cancer (“Lung Cancer 101 | Lungcancer.Org” N.p).
Relevance to Human Society
The cancer patients are affected by the body image and the loss of self- esteem especially after being diagnosed with cancer and being treated. This is because treatment with chemotherapy and other means changes most patients coupled with the emotional knowing of being a fatal disease thus most of the cancer patients have a low self- esteem and show great concern regarding their bodies due to the treatment.
There is also depression where many cancer patients plunge into depression due to the diseases. Fatigue, losing weight by the patients and the occurrence of insomnia are some of the major symptoms that cause such patients to plunge into deep depression. Moreover, the fear that the disease might reoccur on already treated the patient is a major social problem to the patients due to the scientific proof that such illnesses might reoccur in some occasions. There is also the feeling of grief among the family members and the patient especially on reflecting on who the victim was before being infected with the disease. Also, the disease destroys social relationship where many are isolated and abandoned by friends and also families at times. Also, it’s difficult for patients to continue with their working lives due to effects of cancer thus loss of labour to the country band also income (“Social And Emotional Impacts Of Cancer And Cancer Treatment” N.p).
One of the major cultural stigmas that patients undergo is the judgement by the society that patient are to blame for smoking. The society blames the patients for having the disease as their mistake due to lack of adhering to the warning that excessive use of tobacco leads to cancer. Efforts are being raised to encourage awareness on the side effects of the disease, especially among younger generations. The organizations especially NGOs are educating the people on the side effects even the cigar rate producing companies. Indeed cancer has claimed the lives of people like Paul Newman, George Harrison and Andy Kaufman. This famous serve as an example that we should all be aware that lung cancer kills and thus take the necessary measures to control it. Steve Macqueen is an example which people who fought lung cancer together with Tammany Faye proving to us that the disease can be controlled if early treated.

References
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“Lung Cancer 101 | Lungcancer.Org”. Lungcancer.org. Web. 12 Nov. 2016.
Ridge, Carole, Aoife McErlean, and Michelle Ginsberg. “Epidemiology Of Lung Cancer”. PMC. N.p., 2013. Web. 12 Nov. 2016.
“Signs And Symptoms Of Lung Cancer”. Cancer.org. N.p., 2016. Web. 12 Nov. 2016.
“Social And Emotional Impacts Of Cancer And Cancer Treatment”. Oregon Health & Science University. N.p., 2016. Web. 12 Nov. 2016.
Witschi, H. “A Short History Of Lung Cancer”. N.p., 2001. Print.