- June 12, 2020
Abnormalgrowth of cells within the body is commonly known as cancer. Thesetypes of cells can migrate from their site of origin to nearby ordistant tissues and organs. This process is referred to asmetastasis. Human beings are affected by numerous types of cancerwhich are distinguishable depending on the mode of diagnosis andavailable treatment strategies (Stewart and Wild, 2016). This paperaims to concentrate on lung cancer with particular attention on thecauses of the disease, its history, signs/symptoms, transmission,epidemiology, treatment, and finally prevention.
Commonly,this condition is referred to as lung carcinoma in which there existsa malignant tumor within the lung. This leads to the unregulatedgrowth of cells within the tissues found in the lungs. Through theprocess of metastasis, it is possible for the disease to target otherorgans. It is ranked as one of the main causes of mortalityglobally. The primary categories of lung cancer include the smallcell type while the other category is referred to as the non-smallcell type. The major distinction between the two groups is themicroscopic appearance (Ramalingam, Owonikoko, and Khuri, 2011).
Causesof lung cancer
Epigeneticchanges and damage to the genetic material are the main reasons forcancer development. Cell functions such as DNA repair, apoptosis andproliferation are significantly affected. One of the major causativeagents is smoking (Heim and Mitelman, 2015). Nearly all cases of lungcancer emanate from smoking. Numerous toxic substances are present intobacco smoke and are commonly referred to as carcinogens. Some ofthese include polonium-210, ethylene oxide and benzo[a]pyrene. Apartfrom smoking, the utilization of other types of tobacco products suchchewing tobacco or use of cigars predisposes the consumer to thedisease in addition to other associated types of malignancies such asoral cancer. Sadly, it’s not only cigarette smokers who are at riskof developing this disease. Individuals who are exposed to tobaccosmoke are also likely to develop the disease. These are non-smokerswho either live or work with smoking partners. This scenario isreferred to as passive smoking.
Anothercausative agent is known as radon. This is a radioactive gas whichoccurs naturally in the environment, particularly in soils and rockswhich harbor traces of uranium. Some buildings may be found tocontain this component. Inhalation of this gas elevates thelikelihood of developing lung cancer especially among non-smokers(Ramalingam, Owonikoko, and Khuri, 2011).
Additionally,occupational exposure to toxic types of chemicals has alsocontributed significantly in incidences of lung cancer. For example,asbestos and tobacco smoking possess a synergistic effect that has ahigh probability of leading to cancer development. Finally, geneticpredisposition also leads to the development of lung cancer. Familieswith relatives suffering from lung cancer are also likely to developthe disease (Heim and Mitelman, 2015).
Historyof the disease
Beforethe advent of cigarettes, lung cancer was rarely known. In apublication by London-based Thomas Venner written in 1620, he wasable to warn about the dangers of tobacco use. He was able to outlineits effect on the eye, brain, heart and also cause the limbs totremble. In 1761, John Hill, also based in London, added his input toresearch on tobacco. His work was able to guide furtherepidemiological studies in the years to follow. In 1971, lung cancerwas identified as a distinct disease (Proctor, 2012). In 1810,various characteristics of the disease were identified. A significantproportion of cancers emanated from malignant lung tumors. Between1876 and 1938, there were incidences of miners dying from “Mines”which was a disease that affected those working in mining fields. In1878, the proportion was only one percent. However, there was adrastic increase of ten percent and over fourteen percent in 1918 and1927 respectively.
In1929, Fritz Lickint, who was a German physician was able to elaborateon the link between lung cancer and smoking. Through his research,campaigns were initiated against the use of tobacco in Nazi Germany.The year 1940 saw the disease rise to be the second most cause ofdeath resulting from cancer with stomach cancer topping the list. Forthe second time, a connection was established between lung cancer andsmoking as noted by the American Cancer Society in 1954. This wasfurther backed up by the U.S surgeon general, who in 1964 notedsmoking as the leading causative agent of laryngeal and lung cancers.By 2013, more deaths were linked to the disease as compared to othertypes of malignancies (Hajdu and Darvishian, 2013).
Signs/Symptomsof lung cancer
Duringthe early stages of the disease, signs and symptoms are typicallyabsent. These only become visible during the advanced stages of thedisease. This is the stage in which most diagnoses are made.
Thefirst category of symptoms is those associated with the respiratorysystem. The first one being continuous coughing. A cough that hasbeen caused by a cold is likely to fade in a small duration of timehowever, a persistent cough is highly linked to lung cancer. It is,therefore, vital to seek medical attention in case of either a mucoidor a dry cough. Changes in the pattern of a cough should also betaken into consideration. This is particularly significant tosmokers. More specific attention should be given to hoarse or deepercoughs with increased traces of blood or sputum breathingdifficulties may arise due blockage of the airways by tumors or thefluid inside. The production of a wheezing sound while breathingcould also be an indicator of the disease. This results from theinflammation, blockage or constriction of the airways.
Anothercategory of symptoms is broadly referred to as the “systemicsymptoms.” One of this is the significant drop in weight.Unexplained loss of weight may result from the energy consumption bycancerous cells (Bunn Jr, 2012). Additionally, changes in food energyutilization by the body also contributes to the drop. Fever is alsoclassified under this category. Fever is one of the ways in which thebody responds to infection hence it should also be taken intoconsideration especially for smokers.
Thelast category of symptoms is those that occur as a result of thecancerous mass of tissues pressing nearby structures. One of thesymptoms is a pain in the bones. Different parts of the body may beaffected. The pain is usually worse while resting at night. Othersymptoms in this category may include difficulties in ingesting foodand the obstruction of the superior vena cava.
Thespread of lung cancer occurs when the cancerous cells detach from thetumor leading to their spread via the lymphatic system or thebloodstream. This process is commonly referred to as metastasis.Cancer may spread to other distant organs such as the brain andadrenal glands.
Thestandard mode of spread of lung cancer is via the lymphatic system.The tumors that form in the lungs detach into small pieces which passthrough the lymph system, thereby leading to the infection of lymphnodes and other organs such as the brain, heart, and liver (Goldbergetal.,2015). When the cells reach other parts of the body, they attach tohealthy blood vessels. This ultimately introduces the cancerous cellsinto the bloodstream and nutrient supply. This leads to the drasticgrowth of cancerous cells thereby leading to the tumor formation inother body organs. Similar to the lymphatic system, the transmissionalso occurs through the blood channels. Migration, therefore, takesplace from the lung to other vital organs leading to the formation ofsecondary tumors. Even though lung cancer is not transmissible fromone human to the other, there are rare instances when transmissioncan occur. These examples include transplants of organs orhematopoietic stem cells. Cancers that occur during pregnancy maylikely be transmitted to the fetus (Welsh, 2011).
Beforethe twentieth century, incidences of lung cancer were rare. Globally,the most common type of cancer affecting men is lung cancer withrespective to the mortality and incidence rates as per the year 2008(Jemal etal.,2011). As for women, it was the fourth frequently diagnosed type ofcancer however, it ranked second regarding deaths associated withit. Still, in the same year, the disease accounted for thirteenpercent (1.6 million) of the entire cancer cases while forcancer-related deaths, it accounted for eighteen percent (1.4million) globally. The mortality rates and incidences of lung cancerare highest in the developed nations, including the USA and Europe.Despite a slow increase in lung cancer cases in the underdevelopedcountries, the number of cases is still minimal. Most of thesecountries are found in Africa and Latin American. In 2012, thenumber of deaths and new cases increased significantly to 1.56million and 1.82 million respectively (Stewart and Wild, 2016). Themortality rates and incidences of lung cancer in developed countriesare higher in both men and women as opposed to less developed states.
Accordingto the WHO, the increase in the use of tobacco worldwide is estimatedto contribute to the incidences of this disease. Tobacco use is themain risk factor. A significant percentage of the pulmonarycarcinomas are traceable to cigarette smoking. Even though efforts toabolish cigarette smoking have intensified, the number of smokers isstill high, approximated to be 1.1 billion globally. It isapproximated that this figure might increase by the year 2025 to ashocking 1.9 billion (Cruz, Tanoue, and Matthay, 2011). The number ofAmerican adults who were smoking by 2008 was forty-six million. Thenumber represents both daily smokers and non-daily smokers whichrepresent 36.7 million and 9.3 million respectively (Dube etal.,2010).
Inthe USA, the cases of the disease among men has been declining sincethe commencement of the 1980s. There is a direct correlation betweenthe mortality and the incidence rates given that majority of peoplediagnosed with the disease end up succumbing to it. However, thedeath rate among men notably decreased by two percent between theperiods of 1994 to 2006 as noted by Siegel etal.,(2011). In contrast, the death rates in women have increasedsignificantly from the year 1995 to 2005 by 0.3% yearly. However,recent research has shown a reverse of this trend whereby a declineof 0.9% annually has been noted. Due to the reduction in incidencerates among women, the death rate has also dropped. This was longoverdue given that the mortality rate in men declined over a decadeago. The slow decline in the rates of lung cancer among women hadbeen linked to the increase in cigarette smoking which was at itshighest twenty years later than in men. However, the incidences tendto be attaining the plateau stage which good news, as opposed to theincrease, witnessed in the 1970s.
Regardingethnic categorization, dark skinned people are more affected ascompared to other ethnicities. African Americans are at high risk ascompared European Africans and vice versa for their womencounterparts. The difference in the prevalence of smoking has beenthe main reason behind this observation however, it is vital to notethat the increased incidences among African Americans cannot bejustified by the sole reason of cigarette smoking. The AmericanIndians, also referred to as Alaska Native rank second in theincidence rates. Third in the category are Asian or PacificIslanders. The lowest rates have been noted among Hispanics andLatinos.
Amongwomen, the incidence has been high among white women followed by thedark-skinned women. Third on the list are Native Americans followedby Asians and finally Hispanics (Cheng, etal.,2016). All these racial disparities can be traced back to geneticdifferences between the different ethnicities
Manyfactors are taken into consideration when it comes to selecting theappropriate treatment plan. These include the stage, type, generalhealth of the patient and finally, the treatment preference.
Oneof the treatment plans is surgery whereby the tumor in addition toadjacent healthy tissues is removed. Different procedures areinvolved. The whole lobe of one lung may be eliminated through aprocess known as lobectomy, while the removal of an entire lung isreferred to as pneumonectomy. However, in some instances, only asmall piece of the tumor affected is obtained through a processcalled wedge resection. Some piece of healthy tissue is alsoincluded. Sometimes, a huge portion of the lung is removed withoutnecessarily removing the entire lobe. This process is referred to assegmental resection. This treatment is associated with some riskssuch as bleeding and infections (Ramalingam, Owonikoko, and Khuri,2011).
Anothertypical treatment plan is referred to as chemotherapy which involvesthe use of drugs to eliminate the cancerous cells. The drugs may beadministered either orally or intravenously. The treatment is usuallygiven in a series over several weeks or months. This treatment planis always given after a patient has undergone surgery so as to killthe remaining cancerous cells. Additionally, it may be applied beforeto shrink the cancerous cells to ease the ability to remove thecancerous cells.
Thecancerous cells may also be killed through the use of radiationtherapy from sources such as X-rays. It is usually directedexternally towards the lung even though it may be placed insidedevices that are planted close to the cancer site.
Thespecific abnormalities may also be treated with targeted drugtherapy. These are drugs which are commonly used together withchemotherapy drugs. Specific genetic mutations within cancer cellsare usually the targets for some of these drugs hence the testing ofcancer cells before drug administration. Some of these drugs include“nivolumab” and “afatinib.”
Itis mandatory to quit smoking for those who are already smoking whilefor non-smokers, they should only keep off the habit and even avoidexposure to secondary cigarette smoke. Other nicotine replacementproducts can help smokers to keep off the habit.
Peopleshould also test their home for traces of radon, especially if livingin high incidence areas. In the case where elevated levels aredetected, remedies should be initiated before it is rendered safe forhabitation. Workers should also avoid occupational exposure tocarcinogens. Employees should set out the necessary precautionsespecially in occupations where workers handle toxic chemicals. Keeninterest should also be placed on the diet. Vegetables and fruits arevital in lowering the risk of lung cancer. The use of vitaminsupplements is considered ineffective. Finally, it is important to gofor regular screening which is important particularly among theasymptomatic patients (Tammemägi etal.,2013).
Effortsshould be directed towards the cessation of smoking and preventaddiction. The medical profession has to contribute significantly toensuring the primary cause of lung cancer is addressed. Thecurtailing or elimination of tobacco use in addition to addressingother associated exposures may reverse lung cancer to its formercategory of rare diseases.
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