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Latest revision as of 06:28, 28 July 2021

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Dildar Hussain, MBBS [2];Kim-Son H. Nguyen M.D.;Saarah T. Alkhairy M.D;Cafer Zorkun, M.D., Ph.D. [3]

Overview

Prior to the introduction of cigarette smoking and industrial carcinogens, lung cancer was thought to be a rare disease. Of all the tumors detected on autopsy, lung cancer accounted for only 1% of cancers in the 1800s. The majority of cases of lung cancer were associated with occupational hazards due to radon exposure. The association between lung cancer and smoking was not defined until the mid-20th century. Primary lung cancers may be classified into small cell lung cancer (~15%) and non small cell lung cancer (~85%). Non small cell lung cancer are a heterogeneous group of lung cancers that are often grouped together because they share similar clinical features (e.g. prognosis and management). The 2015 WHO histological classification of tumors of the lung categorized lung tumors into malignant epithelial tumors, benign epithelial tumors, lymphoproliferative tumors, miscellaneous tumors, and metastatic tumors. The pathophysiology of lung cancer includes both genetic and environmental factors. Causality of the majority of lung cancer is linked to tobacco usage. Carcinogenic effects of tobacco smoking may result in DNA mis-replication and mutation. Smoking starts a cascade of events that leads to cancer development, even decades after smoking cessation. Besides smokers, patients with the history of prior respiratory tract or gastrointestinal tract cancer comprise a high-risk population. Other environmental factors include radon, asbestos, viral infections, and states of chronic lung inflammation, all of which may predispose to cellular damage and DNA mutations that predispose to the development of lung cancers. The direct cause of lung cancer is DNA mutations that often result in either activation of proto-oncogenes (e.g. K-RAS) or the inactivation of tumors suppressor genes (e.g. TP53) or both. The risk of these genetic mutations may be increased following exposure to environmental insults. Lung cancer must be differentiated from other conditions that cause hemoptysis, cough, dyspnea, wheezing, chest pain, dysphonia, dysphagia, unexplained weight loss, unexplained loss of appetite, and fatigue. These conditions include pneumonia, bronchitis, metastatic cancer from a non-thoracic primary site, infectious granuloma, pulmonary tuberculosis, tracheal tumors, and a thyroid mass. Lung cancer is the most common cause of cancer-associated mortality and the second most common type of cancer among both genders. Individuals > 50 years of age who have a history of smoking are at increased risk. Historically, the incidence of lung cancer is significantly higher among males compared to females. This increased ratio is thought to be attributed to the increased rates of smoking among men. However, more women are being diagnosed with lung cancer due to the increased rate of smoking among women. In 2014, the incidence of lung cancer in the United States was approximately 70 cases per 100,000. The most potent risk factor in the development of lung cancer is tobacco smoking. Other risk factors include second hand smoke, air pollution, family history of lung cancer, radiation therapy to the chest, and exposure to radon, asbestos and other chemical carcinogens. Lung cancer screening is a strategy used to identify early lung cancer in people, before they develop symptoms. Screening refers to the use of medical tests to detect disease in asymptomatic people. Screening studies for lung cancer have only been done in high risk populations, such as smokers and workers with occupational exposure to certain substances. This is because radiation exposure from screening could actually induce carcinogenesis in a small percentage of screened subjects, so this risk should be mitigated by a (relatively) high prevalence of lung cancer in the population being screened. A pulmonary nodule larger than 5 - 6 mm is considered a positive result for screening with x-ray or computed tomography. The majority of lung cancers present with advanced disease because the symptoms tend to occur later in the course of the disease. Patients experience non-specific symptoms such as cough, hemoptysis, dyspnea, chest pain, difficulty speaking, difficulty swallowing, lack of appetite, weight loss, and fatigue from 3 weeks to 3 months before seeking medical attention. There are a variety of complications associated with lung cancer, such as pleural effusion, leg weakness, paresthesias, bladder dysfunction, seizures, hemiplegia, cranial nerve palsies, confusion, personality changes, skeletal pain, pleuritic pain, atelectasis, and bronchopleural fistula. The prognosis of lung cancer is poor if diagnosed at the advanced stages. Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include a solitary pulmonary nodule, centrally located masses, mediastinal invasion CT scans help stage the lung cancer. A CT scan of the abdomen and brain can help visualize the common sights of metastases such as adrenal glands, liver, and brain. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to the nearby structures, and deciphering whether lymph nodes are enlarged in the mediastinum. Common symptoms of lung cancer include difficulty breathing, hemoptysis, chronic coughing, chest pain, weakness and wasting, difficulty speaking, and symptoms related to paraneoplastic syndromes. Common physical examination findings of lung cancer include decreased/absent breath sounds, pallor, low-grade fever, and tachypnea. The laboratory findings associated with lung cancer are the following neutropenia, hyponatremia, hypokalemia, hypercalcemia, respiratory acidosis, hypercarbia, hypoxia, and tumor cells in sputum and pleural effusion cytology. Performing a chest x-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. Lung cancers are usually detected on a routine chest x-ray in a person experiencing no symptoms. There are no echocardiography/ultrasound findings associated with lung cancer. Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include a solitary pulmonary nodule, centrally located masses, mediastinal invasion CT scans help stage the lung cancer. A CT scan of the abdomen and brain can help visualize the common sights of metastases such as adrenal glands, liver, and brain. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to the nearby structures, and deciphering whether lymph nodes are enlarged in the mediastinum. The indication of MRI in lung cancer is when there is a suspicion of spinal cord canal invasion and/or in the presence of pancoast tumor (superior sulcus tumor) and brachial plexus tumors. There are no other imaging findings associated with lung cancer. Other diagnostic studies include bone scintigraphy, PET scan, and molecular tests. Medical therapy for lung cancer consists of radiation therapy, chemotherapy, and targeted therapy. Lung cancer surgery involves the surgical excision of the cancerous tissue. It is used mainly in non-small cell lung cancer with the intention of curing the patient. Effective measures for the primary prevention of lung cancer include smoking cessation and avoidance of second hand smoking. Lifestyle changes, such as healthy diet rich with fruits and vegetables and regular exercise, might decrease the risk of developing cancer in general. Secondary prevention of lung cancer consists of smoking cessation and screening. Secondary chemoprevention focuses on blocking the development of lung cancer in individuals in whom a precancerous lesion has been detected.

Historical Perspective

Prior to the introduction of cigarette smoking and industrial carcinogens, lung cancer was thought to be a rare disease. Of all the tumors detected on autopsy, lung cancer accounted for only 1% of cancers in the 1800s. The majority of cases of lung cancer were associated with occupational hazards due to radon exposure. The association between lung cancer and smoking was not defined until the mid-20th century.

Classification

Primary lung cancers may be classified into small cell lung cancer (~15%) and non small cell lung cancer (~85%). Non small cell lung cancer are a heterogeneous group of lung cancers that are often grouped together because they share similar clinical features (e.g. prognosis and management). The 2015 WHO histological classification of tumors of the lung categorized lung tumors into malignant epithelial tumors, benign epithelial tumors, lymphoproliferative tumors, miscellaneous tumors, and metastatic tumors.

Pathophysiology

The pathophysiology of lung cancer includes both genetic and environmental factors. Causality of the majority of lung cancer is linked to tobacco usage. Carcinogenic effects of tobacco smoking may result in DNA mis-replication and mutation. Smoking starts a cascade of events that leads to cancer development, even decades after smoking cessation. Besides smokers, patients with the history of prior respiratory tract or gastrointestinal tract cancer comprise a high-risk population. Other environmental factors include radon, asbestos, viral infections, and states of chronic lung inflammation, all of which may predispose to cellular damage and DNA mutations that predispose to the development of lung cancers.

Causes

The direct cause of lung cancer is DNA mutations that often result in either activation of proto-oncogenes (e.g. K-RAS) or the inactivation of tumors suppressor genes (e.g. TP53) or both. The risk of these genetic mutations may be increased following exposure to environmental insults.

Differential Diagnosis

Lung cancer must be differentiated from other conditions that cause hemoptysis, cough, dyspnea, wheezing, chest pain, dysphonia, dysphagia, unexplained weight loss, unexplained loss of appetite, and fatigue. These conditions include pneumonia, bronchitis, metastatic cancer from a non-thoracic primary site, infectious granuloma, pulmonary tuberculosis, tracheal tumors, and a thyroid mass.

Epidemiology and Demographics

Lung cancer is the most common cause of cancer-associated mortality and the second most common type of cancer among both genders. Individuals > 50 years of age who have a history of smoking are at increased risk. Historically, the incidence of lung cancer is significantly higher among males compared to females. This increased ratio is thought to be attributed to the increased rates of smoking among men. However, more women are being diagnosed with lung cancer due to the increased rate of smoking among women. In 2014, the incidence of lung cancer in the United States was approximately 70 cases per 100,000.

Risk Factors

The most potent risk factor in the development of lung cancer is tobacco smoking. Other risk factors include second hand smoke, air pollution, family history of lung cancer, radiation therapy to the chest, and exposure to radon, asbestos and other chemical carcinogens.

Screening

Lung cancer screening is a strategy used to identify early lung cancer in people, before they develop symptoms. Screening refers to the use of medical tests to detect disease in asymptomatic people. Screening studies for lung cancer have only been done in high risk populations, such as smokers and workers with occupational exposure to certain substances. This is because radiation exposure from screening could actually induce carcinogenesis in a small percentage of screened subjects, so this risk should be mitigated by a (relatively) high prevalence of lung cancer in the population being screened. A pulmonary nodule larger than 5 - 6 mm is considered a positive result for screening with x-ray or computed tomography.

Natural History, Complications, and Prognosis

The majority of lung cancers present with advanced disease because the symptoms tend to occur later in the course of the disease. Patients experience non-specific symptoms such as cough, hemoptysis, dyspnea, chest pain, difficulty speaking, difficulty swallowing, lack of appetite, weight loss, and fatigue from 3 weeks to 3 months before seeking medical attention. There are a variety of complications associated with lung cancer, such as pleural effusion, leg weakness, paresthesias, bladder dysfunction, seizures, hemiplegia, cranial nerve palsies, confusion, personality changes, skeletal pain, pleuritic pain, atelectasis, and bronchopleural fistula. The prognosis of lung cancer is poor if diagnosed at the advanced stages.

Diagnosis

Diagnostic Study of Choice

Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include a solitary pulmonary nodule, centrally located masses, mediastinal invasion CT scans help stage the lung cancer. A CT scan of the abdomen and brain can help visualize the common sights of metastases such as adrenal glands, liver, and brain. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to the nearby structures, and deciphering whether lymph nodes are enlarged in the mediastinum.

History and Symptoms

Common symptoms of lung cancer include difficulty breathing, hemoptysis, chronic coughing, chest pain, weakness and wasting, difficulty speaking, and symptoms related to paraneoplastic syndromes.

Physical Examination

Common physical examination findings of lung cancer include decreased/absent breath sounds, pallor, low-grade fever, and tachypnea.

Diagnostic Studies

Diagnostic study of choice

Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include, a solitary pulmonary nodule, centrally located masses, mediastinal invasion. A CT scan of the abdomen and brain can help visualize the common sites of metastases: adrenal glands, liver, and brain. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to nearby structures, and deciphering whether lymph nodes are enlarged in the mediastinum.

Laboratory Findings

The laboratory findings associated with lung cancer are the following neutropenia, hyponatremia, hypokalemia, hypercalcemia, respiratory acidosis, hypercarbia, hypoxia, and tumor cells in sputum and pleural effusion cytology.

Electrocardiograpgy

ECG is a simple method for finding evidence of pulmonary artery stenosis in metastatic lung cancer and should be routinely performed in such patients. Findings on ECG associated mediastinal metastatic of lung cancer led to pulmonary artery stenosis and right ventricular strain include right axis deviation, deepened S wave in lead 1, sustantial R wave in lead avR, inverted/flattened T waves in limb and precordial leads.

X-ray

Performing a chest x-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. Lung cancers are usually detected on a routine chest x-ray in a person experiencing no symptoms.

Echocardiography and Ultrasound

There are no echocardiography/ultrasound findings associated with lung cancer.

CT scan

Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include a solitary pulmonary nodule, centrally located masses, mediastinal invasion CT scans help stage the lung cancer. A CT scan of the abdomen and brain can help visualize the common sights of metastases such as adrenal glands, liver, and brain. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to the nearby structures, and deciphering whether lymph nodes are enlarged in the mediastinum.

MRI

The indication of MRI in lung cancer is when there is a suspicion of spinal cord canal invasion and/or in the presence of pancoast tumor (superior sulcus tumor) and brachial plexus tumors.

Other Imaging Findings

There are no other imaging findings associated with lung cancer.

Other Diagnostic Studies

Other diagnostic studies include bone scintigraphy, PET scan, and molecular tests.

Treatment

Medical Therapy

Medical therapy for lung cancer consists of radiation therapy, chemotherapy, and targeted therapy.

Surgery

Lung cancer surgery involves the surgical excision of the cancerous tissue. It is used mainly in non-small cell lung cancer with the intention of curing the patient.

Primary Prevention

Effective measures for the primary prevention of lung cancer include smoking cessation and avoidance of second hand smoking. Lifestyle changes, such as healthy diet rich with fruits and vegetables and regular exercise, might decrease the risk of developing cancer in general.

Secondary Prevention

Secondary prevention of lung cancer consists of smoking cessation and screening. Secondary chemoprevention focuses on blocking the development of lung cancer in individuals in whom a precancerous lesion has been detected.

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-{{CMG}}; '''Associate Editor(s)-In-Chief:''' Kim-Son H. Nguyen, M.D., M.P.A., Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA, {{CZ}}
+__NOTOC__
+{{Lung cancer}}
+{{CMG}}; {{AE}}  {{SH}};{{KSH}};{{STA}};{{CZ}}
 ==Overview==
+Prior to the introduction of [[cigarette]] [[smoking]] and industrial [[carcinogens]], lung cancer was thought to be a [[rare disease]]. Of all the [[tumors]] detected on [[autopsy]], lung cancer accounted for only 1% of [[cancers]] in the 1800s. The majority of cases of lung cancer were associated with occupational hazards due to [[radon]] exposure. The association between lung cancer and [[smoking]] was not defined until the mid-20th century. Primary lung cancers may be [[Classification|classified]] into [[small cell lung cancer]] (~15%) and [[non small cell lung cancer]] (~85%).  [[Non small cell lung cancer]] are a [[heterogeneous]] group of lung cancers that are often grouped together because they share similar clinical features (e.g. [[prognosis]] and management). The 2015 [[World Health Organization|WHO]] [[Histology|histological]] [[classification]] of [[tumors]] of the [[lung]] categorized [[lung]] [[tumors]] into [[malignant]] [[epithelial]] [[tumors]], [[benign]] [[epithelial]] [[tumors]], [[Lymphoproliferative disorders|lymphoproliferative tumors]], miscellaneous [[tumors]], and [[metastatic]] [[tumors]]. The [[pathophysiology]] of lung cancer includes both [[genetic]] and [[Environmental factor|environmental factors]]. [[Causality]] of the majority of lung cancer is linked to [[Tobacco|tobacco usage.]] [[Carcinogen|Carcinogenic]] effects of [[tobacco smoking]] may result in [[DNA]] mis-replication and [[mutation]]. [[Smoking]] starts a [[cascade]] of events that leads to [[cancer]] development, even decades after [[smoking cessation]]. Besides [[Smoking|smokers]], [[Patient|patients]] with the history of prior [[Respiratory tract neoplasm|respiratory tract]] or [[gastrointestinal tract cancer]] comprise a high-risk population. Other [[Environmental factor|environmental factors]] include [[radon]], [[asbestos]], [[viral infections]], and states of [[Pulmonary inflammation|chronic lung inflammation]], all of which may [[Predisposition|predispose]] to [[cellular]] damage and [[DNA mutations]] that [[Predisposition|predispose]] to the development of lung cancers. The direct cause of lung cancer is [[DNA mutations]] that often result in either activation of [[Proto-oncogene|proto-oncogenes]] (e.g. '''[[KRAS|K-RAS]]''') or the inactivation of [[Tumor suppressor gene|tumors suppressor genes]] (e.g. '''[[TP53]]''') or both. The risk of these [[genetic mutations]] may be increased following exposure to environmental insults. Lung cancer must be differentiated from other conditions that cause [[hemoptysis]], [[cough]], [[dyspnea]], [[Wheeze|wheezing]], [[chest pain]], [[dysphonia]], [[dysphagia]], unexplained [[weight loss]], unexplained [[loss of appetite]], and [[fatigue]]. These conditions include [[pneumonia]], [[bronchitis]], [[metastatic cancer]] from a non-[[Chest|thoracic]] primary site, [[infectious]] [[granuloma]], [[Tuberculosis|pulmonary tuberculosis]], [[Trachea|tracheal]] [[Tumor|tumors]], and a [[thyroid]] mass. Lung cancer is the most common cause of [[cancer]]-associated [[mortality]] and the second most common type of [[cancer]] among both genders. Individuals > 50 years of age who have a history of [[smoking]] are at increased risk. Historically, the [[incidence]] of lung cancer is significantly higher among [[Male|males]] compared to [[Female|females]]. This increased ratio is thought to be attributed to the increased rates of [[smoking]] among [[Male|men]]. However, more [[Female|women]] are being [[Diagnosis|diagnosed]] with lung cancer due to the increased rate of [[smoking]] among [[Female|women]]. In 2014, the [[incidence]] of [[lung cancer]] in the United States was approximately 70 cases per 100,000. The most potent [[risk factor]] in the development of lung cancer is [[tobacco]] [[smoking]]. Other [[Risk factor|risk factors]] include [[Passive smoking|second hand smoke]], [[air pollution]], [[family history]] of lung cancer, [[radiation therapy]] to the [[chest]], and exposure to [[radon]], [[asbestos]] and other [[chemical]] [[carcinogens]]. Lung cancer [[Screening (medicine)|screening]] is a strategy used to identify early lung cancer in people, before they develop [[Symptom|symptoms]]. [[Screening (medicine)|Screening]] refers to the use of [[Medicine|medical]] [[Test|tests]] to detect [[disease]] in [[asymptomatic]] people. [[Screening (medicine)|Screening]] studies for lung cancer have only been done in high risk populations, such as [[Smoking|smokers]] and workers with occupational exposure to certain substances. This is because [[radiation exposure]] from [[Screening (medicine)|screening]] could actually induce [[carcinogenesis]] in a small percentage of [[Screening|screened]] subjects, so this risk should be mitigated by a (relatively) high [[prevalence]] of lung cancer in the population being [[Screening|screened]]. A [[pulmonary nodule]] larger than 5 - 6 mm is considered a positive result for [[Screening (medicine)|screening]] with [[x-ray]] or [[computed tomography]]. The majority of lung cancers present with advanced [[disease]] because the [[symptoms]] tend to occur later in the course of the [[disease]]. [[Patient|Patients]] experience non-specific [[Symptom|symptoms]] such as [[cough]], [[hemoptysis]], [[dyspnea]], [[chest pain]], [[Dysphonia|difficulty speaking]], [[Dysphagia|difficulty swallowing]], [[lack of appetite]], [[weight loss]], and [[fatigue]] from 3 weeks to 3 months before seeking medical attention. There are a variety of [[complications]] associated with lung cancer, such as [[pleural effusion]], [[leg weakness]], [[paresthesias]], [[Urinary bladder|bladder]] dysfunction, [[seizures]], [[hemiplegia]], [[cranial nerve palsies]], [[confusion]], [[personality changes]], [[Skeleton|skeletal]] [[pain]], [[pleuritic pain]], [[atelectasis]], and [[bronchopleural fistula]]. The [[prognosis]] of lung cancer is poor if [[Diagnosis|diagnosed]] at the advanced stages. [[Chest]] [[Computed tomography|CT scan]] is the modality of choice in the [[diagnosis]] of lung cancer. Findings on [[Computed tomography|CT scan]] suggestive of lung cancer include a [[Pulmonary nodule|solitary pulmonary nodule]], centrally located [[Tumor|masses]], [[Mediastinum|mediastinal]] [[Invasive (medical)|invasion]] [[Computed tomography|CT scans]] help [[Cancer staging|stage]] the lung cancer. A [[Computed tomography|CT scan]] of the [[abdomen]] and [[brain]] can help visualize the common sights of [[Metastasis|metastases]] such as [[Adrenal gland|adrenal glands]], [[liver]], and [[brain]]. [[Computed tomography|CT scans]] [[Diagnosis|diagnose]] lung cancer by providing [[anatomical]] detail to locate the [[tumor]], demonstrating proximity to the nearby structures, and deciphering whether [[lymph nodes]] are enlarged in the [[mediastinum]]. Common symptoms of lung cancer include [[Dyspnea|difficulty breathing]], [[hemoptysis]], [[Chronic cough|chronic coughing]], [[chest pain]], [[Cachexia|weakness and wasting]], [[Dysphonia|difficulty speaking]], and [[Symptom|symptoms]] related to [[paraneoplastic syndromes]]. Common [[physical examination]] findings of lung cancer include decreased/absent [[breath sounds]], [[pallor]], low-grade [[fever]], and [[tachypnea]]. The [[Medical laboratory|laboratory]] findings associated with lung cancer are the following [[neutropenia]], [[hyponatremia]], [[hypokalemia]], [[hypercalcemia]], [[respiratory acidosis]], [[hypercarbia]], [[hypoxia]], and [[Tumor cell|tumor cells]] in [[sputum]] and [[pleural effusion]] [[cytology]]. Performing a [[chest x-ray]] is the first step if a [[patient]] reports [[Symptom|symptoms]] that may be suggestive of lung cancer. Lung cancers are usually detected on a routine [[Chest X-ray|chest x-ray]] in a person experiencing no [[Symptom|symptoms]]. There are no [[echocardiography]]/[[ultrasound]] findings associated with lung cancer. [[Chest]] [[Computed tomography|CT scan]] is the modality of choice in the [[diagnosis]] of lung cancer. Findings on [[Computed tomography|CT scan]] suggestive of lung cancer include a [[Pulmonary nodule|solitary pulmonary nodule]], centrally located [[Tumor|masses]], [[Mediastinum|mediastinal]] [[Invasive (medical)|invasion]] [[Computed tomography|CT scans]] help [[Cancer staging|stage]] the lung cancer. A [[Computed tomography|CT scan]] of the [[abdomen]] and [[brain]] can help visualize the common sights of [[Metastasis|metastases]] such as [[Adrenal gland|adrenal glands]], [[liver]], and [[brain]]. [[Computed tomography|CT scans]] [[Diagnosis|diagnose]] lung cancer by providing [[anatomical]] detail to locate the [[tumor]], demonstrating proximity to the nearby structures, and deciphering whether [[lymph nodes]] are enlarged in the [[mediastinum]]. The [[Indication (medicine)|indication]] of [[Magnetic resonance imaging|MRI]] in lung cancer is when there is a suspicion of [[spinal cord]] canal [[Invasive (medical)|invasion]] and/or in the presence of [[pancoast tumor]] ([[Sulcus (anatomy)|superior sulcus]] [[tumor]]) and [[brachial plexus]] [[Tumor|tumors]]. There are no other [[imaging]] findings associated with lung cancer. Other [[Diagnosis|diagnostic]] studies include [[bone]] [[scintigraphy]], [[PET scan]], and [[molecular]] [[Test|tests]]. [[Medical]] [[therapy]] for lung cancer consists of [[radiation therapy]], [[chemotherapy]], and targeted [[therapy]]. Lung cancer [[surgery]] involves the [[Excision|surgical excision]] of the [[Cancer|cancerous]] [[Tissue (biology)|tissue]]. It is used mainly in [[non-small cell lung cancer]] with the intention of [[Cure|curing]] the [[patient]]. Effective measures for the [[Prevention (medical)|primary prevention]] of lung cancer include [[smoking cessation]] and avoidance of [[Passive smoking|second hand smoking]]. Lifestyle changes, such as [[Health|healthy]] [[Diet (nutrition)|diet]] rich with [[Fruit|fruits]] and [[Vegetable|vegetables]] and regular [[Physical exercise|exercise]], might decrease the risk of developing cancer in general. [[Prevention (medical)|Secondary prevention]] of lung cancer consists of [[smoking cessation]] and [[Screening (medicine)|screening]]. Secondary chemoprevention focuses on blocking the development of lung cancer in individuals in whom a [[precancerous]] [[lesion]] has been detected.
-'''Lung cancer''', or '''carcinoma of the lung''', is a [[disease]] where [[epithelium|epithelial]] (internal lining) [[tissue (biology)|tissue]] in the [[lung]] [[cell growth|grows]] out of control. This leads to [[metastasis]], invasion of adjacent tissue and infiltration beyond the lungs. Lung [[cancer]], the most common cause of cancer-related death in men and the second most common in women,<ref name="WHO2">{{cite web | last =WHO | authorlink =World Health Organization | title =Deaths by cause, sex and mortality stratum | publisher =World Health Organization | date =2004 | url =http://www.who.int/whr/2004/annex/topic/en/annex_2_en.pdf | format = PDF| accessdate =2007-06-01 }}</ref><ref name="NLCP">{{cite web | authorlink = | coauthors = | title =Lung Cancer Facts (Women) | publisher = National Lung Cancer Partnership | date =2006 | url =http://www.nationallungcancerpartnership.org/page.cfm?l=factsWomen | accessdate =2007-05-26 }}</ref> is responsible for 1.3 million deaths worldwide
+==Historical Perspective ==
-annually.<ref name="WHO">{{cite web | last =WHO | authorlink =World Health Organization | title =Cancer | publisher =World Health Organization | date =February 2006 | url =http://www.who.int/mediacentre/factsheets/fs297/en/ | accessdate =2007-06-25 }}</ref> The most common [[symptom]]s are shortness of breath, coughing (including [[Hemoptysis|coughing up blood]]), and weight loss.<ref name="Harrison">{{cite book | last =Minna | first =JD | title =Harrison's Principle's of Internal Medicine | publisher=McGraw-Hill | date =2004 | pages =506–516 | doi =10.1036/0071402357 | isbn =0071391401 }}</ref>
+Prior to the introduction of [[cigarette]] [[smoking]] and industrial [[carcinogens]], lung cancer was thought to be a [[rare disease]]. Of all the [[tumors]] detected on [[autopsy]], lung cancer accounted for only 1% of [[cancers]] in the 1800s. The majority of cases of lung cancer were associated with occupational hazards due to [[radon]] exposure. The association between lung cancer and [[smoking]] was not defined until the mid-20th century.
-The main types of lung cancer are ''small cell lung carcinoma'' and ''non-small cell lung carcinoma''. This distinction is important because the treatment varies; non-small cell lung carcinoma (NSCLC) is sometimes treated with [[lung cancer surgery|surgery]], while small cell lung carcinoma (SCLC) usually responds better to [[chemotherapy]].
+==Classification==
+Primary lung cancers may be [[Classification|classified]] into [[small cell lung cancer]] (~15%) and [[non small cell lung cancer]] (~85%).  [[Non small cell lung cancer]] are a [[heterogeneous]] group of lung cancers that are often grouped together because they share similar clinical features (e.g. [[prognosis]] and management). The 2015 [[World Health Organization|WHO]] [[Histology|histological]] [[classification]] of [[tumors]] of the [[lung]] categorized [[lung]] [[tumors]] into [[malignant]] [[epithelial]] [[tumors]], [[benign]] [[epithelial]] [[tumors]], [[Lymphoproliferative disorders|lymphoproliferative tumors]], miscellaneous [[tumors]], and [[metastatic]] [[tumors]].
-The most common cause of lung cancer is exposure to [[tobacco smoking|tobacco smoke]]. The occurrence of lung cancer in non-smokers, who account for fewer than 10% of cases, appears to be due to a combination of [[genetics|genetic factors]].<ref name="Gorlova">{{cite journal | last =Gorlova | first =OY | coauthors =Weng SF, Zhang Y et al. | title =Aggregation of cancer among relatives of never-smoking lung cancer patients | journal = International Journal of Cancer | volume = 121 | issue = 1 | pages = 111–118 | date =Jul 2007 | pmid =17304511 }}</ref><ref name="Hackshaw">{{cite journal | last =Hackshaw | first =AK | coauthors =Law MR, Wald NJ | title =The accumulated evidence on lung cancer and environmental tobacco smoke | journal =British Medical Journal | volume =315 | issue =7114 | pages =980–988 | date =Oct 1997 | url =http://www.bmj.com/cgi/content/full/315/7114/980  | pmid =9365295 | accessdate =2007-08-10 }}</ref> [[Radon]] gas, [[asbestos]], and [[air pollution]]<ref name="Kabir">{{cite journal | last = Kabir | first = Z | coauthors = Bennett K, Clancy L | title = Lung cancer and urban air-pollution in dublin: a temporal association? | journal = Irish Medical Journal | volume = 100 | issue = 2 | pages = 367–369 | date =Feb 2007 | pmid =17432813 }}</ref><ref name="Coyle">{{cite journal | last = Coyle | first = YM | coauthors = Minahjuddin AT, Hynan LS, Minna JD | title = An ecological study of the association of metal air pollutants with lung cancer incidence in Texas. | journal = Journal of Thoracic Oncology | volume = 1 | issue = 7 | pages = 654–661 | date =Sep 2006 | pmid =17409932 }}</ref><ref name="Chiu">{{cite journal | last = Chiu | first = HF | coauthors = Cheng MH, Tsai SS et al. | title = Outdoor air pollution and female lung cancer in Taiwan. | journal = Inhalation Toxicology | volume = 18 | issue = 13 | pages = 1025–1031 | date = Dec 2006 | pmid =16966302 }}</ref> may also contribute to lung cancer.
+==Pathophysiology==
+The [[pathophysiology]] of lung cancer includes both [[genetic]] and [[Environmental factor|environmental factors]]. [[Causality]] of the majority of lung cancer is linked to [[Tobacco|tobacco usage.]] [[Carcinogen|Carcinogenic]] effects of [[tobacco smoking]] may result in [[DNA]] mis-replication and [[mutation]]. [[Smoking]] starts a [[cascade]] of events that leads to [[cancer]] development, even decades after [[smoking cessation]]. Besides [[Smoking|smokers]], [[Patient|patients]] with the history of prior [[Respiratory tract neoplasm|respiratory tract]] or [[gastrointestinal tract cancer]] comprise a high-risk population. Other [[Environmental factor|environmental factors]] include [[radon]], [[asbestos]], [[viral infections]], and states of [[Pulmonary inflammation|chronic lung inflammation]], all of which may [[Predisposition|predispose]] to [[cellular]] damage and [[DNA mutations]] that [[Predisposition|predispose]] to the development of lung cancers.
-Lung cancer may be seen on [[chest x-ray]] and [[computed tomography]] (CT scan). The [[diagnosis]] is confirmed with a [[biopsy]]. This is usually performed via [[bronchoscopy]] or CT-guided biopsy.
+==Causes==
+The direct cause of lung cancer is [[DNA mutations]] that often result in either activation of [[Proto-oncogene|proto-oncogenes]] (e.g. '''[[KRAS|K-RAS]]''') or the inactivation of [[Tumor suppressor gene|tumors suppressor genes]] (e.g. '''[[TP53]]''') or both. The risk of these [[genetic mutations]] may be increased following exposure to environmental insults.
-Treatment and [[prognosis]] depend upon the [[histology|histological]] type of cancer, the [[staging (pathology)|stage]] (degree of spread), and the patient's [[performance status]]. Possible treatments include surgery, chemotherapy, and [[radiation therapy|radiotherapy]]. With treatment, the five-year [[survival rate]] is 14%.<ref name="Harrison"/>
+==Differential Diagnosis==
+Lung cancer must be differentiated from other conditions that cause [[hemoptysis]], [[cough]], [[dyspnea]], [[Wheeze|wheezing]], [[chest pain]], [[dysphonia]], [[dysphagia]], unexplained [[weight loss]], unexplained [[loss of appetite]], and [[fatigue]]. These conditions include [[pneumonia]], [[bronchitis]], [[metastatic cancer]] from a non-[[Chest|thoracic]] primary site, [[infectious]] [[granuloma]], [[Tuberculosis|pulmonary tuberculosis]], [[Trachea|tracheal]] [[Tumor|tumors]], and a [[thyroid]] mass.
+==Epidemiology and Demographics==
+Lung cancer is the most common cause of [[cancer]]-associated [[mortality]] and the second most common type of [[cancer]] among both genders. Individuals > 50 years of age who have a history of [[smoking]] are at increased risk. Historically, the [[incidence]] of lung cancer is significantly higher among [[Male|males]] compared to [[Female|females]]. This increased ratio is thought to be attributed to the increased rates of [[smoking]] among [[Male|men]]. However, more [[Female|women]] are being [[Diagnosis|diagnosed]] with lung cancer due to the increased rate of [[smoking]] among [[Female|women]]. In 2014, the [[incidence]] of [[lung cancer]] in the United States was approximately 70 cases per 100,000.
+==Risk Factors==
+The most potent [[risk factor]] in the development of lung cancer is [[tobacco]] [[smoking]]. Other [[Risk factor|risk factors]] include [[Passive smoking|second hand smoke]], [[air pollution]], [[family history]] of lung cancer, [[radiation therapy]] to the [[chest]], and exposure to [[radon]], [[asbestos]] and other [[chemical]] [[carcinogens]].
+==Screening==
+Lung cancer [[Screening (medicine)|screening]] is a strategy used to identify early lung cancer in people, before they develop [[Symptom|symptoms]]. [[Screening (medicine)|Screening]] refers to the use of [[Medicine|medical]] [[Test|tests]] to detect [[disease]] in [[asymptomatic]] people. [[Screening (medicine)|Screening]] studies for lung cancer have only been done in high risk populations, such as [[Smoking|smokers]] and workers with occupational exposure to certain substances. This is because [[radiation exposure]] from [[Screening (medicine)|screening]] could actually induce [[carcinogenesis]] in a small percentage of [[Screening|screened]] subjects, so this risk should be mitigated by a (relatively) high [[prevalence]] of lung cancer in the population being [[Screening|screened]]. A [[pulmonary nodule]] larger than 5 - 6 mm is considered a positive result for [[Screening (medicine)|screening]] with [[x-ray]] or [[computed tomography]].
+==Natural History, Complications, and Prognosis==
+The majority of lung cancers present with advanced [[disease]] because the [[symptoms]] tend to occur later in the course of the [[disease]]. [[Patient|Patients]] experience non-specific [[Symptom|symptoms]] such as [[cough]], [[hemoptysis]], [[dyspnea]], [[chest pain]], [[Dysphonia|difficulty speaking]], [[Dysphagia|difficulty swallowing]], [[lack of appetite]], [[weight loss]], and [[fatigue]] from 3 weeks to 3 months before seeking medical attention. There are a variety of [[complications]] associated with lung cancer, such as [[pleural effusion]], [[leg weakness]], [[paresthesias]], [[Urinary bladder|bladder]] dysfunction, [[seizures]], [[hemiplegia]], [[cranial nerve palsies]], [[confusion]], [[personality changes]], [[Skeleton|skeletal]] [[pain]], [[pleuritic pain]], [[atelectasis]], and [[bronchopleural fistula]]. The [[prognosis]] of lung cancer is poor if [[Diagnosis|diagnosed]] at the advanced stages.
+==Diagnosis==
+=== Diagnostic Study of Choice ===
+[[Chest]] [[Computed tomography|CT scan]] is the modality of choice in the [[diagnosis]] of lung cancer. Findings on [[Computed tomography|CT scan]] suggestive of lung cancer include a [[Pulmonary nodule|solitary pulmonary nodule]], centrally located [[Tumor|masses]], [[Mediastinum|mediastinal]] [[Invasive (medical)|invasion]] [[Computed tomography|CT scans]] help [[Cancer staging|stage]] the lung cancer. A [[Computed tomography|CT scan]] of the [[abdomen]] and [[brain]] can help visualize the common sights of [[Metastasis|metastases]] such as [[Adrenal gland|adrenal glands]], [[liver]], and [[brain]]. [[Computed tomography|CT scans]] [[Diagnosis|diagnose]] lung cancer by providing [[anatomical]] detail to locate the [[tumor]], demonstrating proximity to the nearby structures, and deciphering whether [[lymph nodes]] are enlarged in the [[mediastinum]].
+===History and Symptoms===
+Common symptoms of lung cancer include [[Dyspnea|difficulty breathing]], [[hemoptysis]], [[Chronic cough|chronic coughing]], [[chest pain]], [[Cachexia|weakness and wasting]], [[Dysphonia|difficulty speaking]], and [[Symptom|symptoms]] related to [[paraneoplastic syndromes]].
+===Physical Examination===
+Common [[physical examination]] findings of lung cancer include decreased/absent [[breath sounds]], [[pallor]], low-grade [[fever]], and [[tachypnea]].
+==Diagnostic Studies==
+=== Diagnostic study of choice ===
+[[CT scan|Chest CT scan]] is the modality of choice in the diagnosis of lung cancer. Findings on [[CT scan]] suggestive of lung cancer include, a [[solitary pulmonary nodule]], centrally located masses, [[Mediastinal Mass|mediastinal invasion]]. A CT scan of the [[abdomen]] and [[brain]] can help visualize the common sites of [[metastases]]: [[adrenal glands]], [[liver]], and [[brain]]. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to nearby structures, and deciphering whether [[lymph nodes]] are enlarged in the [[mediastinum]].
+===Laboratory Findings===
+The [[Medical laboratory|laboratory]] findings associated with lung cancer are the following [[neutropenia]], [[hyponatremia]], [[hypokalemia]], [[hypercalcemia]], [[respiratory acidosis]], [[hypercarbia]], [[hypoxia]], and [[Tumor cell|tumor cells]] in [[sputum]] and [[pleural effusion]] [[cytology]].
+===[[Electrocardiograpgy]]===
+[[ECG]] is a simple [[method]] for finding evidence of [[pulmonary artery stenosis]] in [[metastatic]] [[lung cancer]] and should be routinely performed in such [[patients]]. Findings on [[ECG]] associated [[mediastinal]] [[metastatic]] of [[lung cancer]] led to [[pulmonary artery stenosis]] and [[right ventricular]] [[strain]] include [[right axis deviation]], deepened S wave in lead 1, sustantial R wave in lead avR, inverted/flattened T waves in [[limb]] and [[precordial]] [[leads]].
+===X-ray===
+Performing a [[chest x-ray]] is the first step if a [[patient]] reports [[Symptom|symptoms]] that may be suggestive of lung cancer. Lung cancers are usually detected on a routine [[Chest X-ray|chest x-ray]] in a person experiencing no [[Symptom|symptoms]].
+===Echocardiography and Ultrasound ===
+There are no [[echocardiography]]/[[ultrasound]] findings associated with lung cancer.
+===CT scan===
+[[Chest]] [[Computed tomography|CT scan]] is the modality of choice in the [[diagnosis]] of lung cancer. Findings on [[Computed tomography|CT scan]] suggestive of lung cancer include a [[Pulmonary nodule|solitary pulmonary nodule]], centrally located [[Tumor|masses]], [[Mediastinum|mediastinal]] [[Invasive (medical)|invasion]] [[Computed tomography|CT scans]] help [[Cancer staging|stage]] the lung cancer. A [[Computed tomography|CT scan]] of the [[abdomen]] and [[brain]] can help visualize the common sights of [[Metastasis|metastases]] such as [[Adrenal gland|adrenal glands]], [[liver]], and [[brain]]. [[Computed tomography|CT scans]] [[Diagnosis|diagnose]] lung cancer by providing [[anatomical]] detail to locate the [[tumor]], demonstrating proximity to the nearby structures, and deciphering whether [[lymph nodes]] are enlarged in the [[mediastinum]].
+===MRI===
+The [[Indication (medicine)|indication]] of [[Magnetic resonance imaging|MRI]] in lung cancer is when there is a suspicion of [[spinal cord]] canal [[Invasive (medical)|invasion]] and/or in the presence of [[pancoast tumor]] ([[Sulcus (anatomy)|superior sulcus]] [[tumor]]) and [[brachial plexus]] [[Tumor|tumors]].
+===Other Imaging Findings===
+There are no other [[imaging]] findings associated with lung cancer.
+===Other Diagnostic Studies===
+Other [[Diagnosis|diagnostic]] studies include [[bone]] [[scintigraphy]], [[PET scan]], and [[molecular]] [[Test|tests]].
+==Treatment==
+===Medical Therapy===
+[[Medical]] [[therapy]] for lung cancer consists of [[radiation therapy]], [[chemotherapy]], and targeted [[therapy]].
+===Surgery===
+Lung cancer [[surgery]] involves the [[Excision|surgical excision]] of the [[Cancer|cancerous]] [[Tissue (biology)|tissue]]. It is used mainly in [[non-small cell lung cancer]] with the intention of [[Cure|curing]] the [[patient]].
+===Primary Prevention===
+Effective measures for the [[Prevention (medical)|primary prevention]] of lung cancer include [[smoking cessation]] and avoidance of [[Passive smoking|second hand smoking]]. Lifestyle changes, such as [[Health|healthy]] [[Diet (nutrition)|diet]] rich with [[Fruit|fruits]] and [[Vegetable|vegetables]] and regular [[Physical exercise|exercise]], might decrease the risk of developing cancer in general.
+===Secondary Prevention===
+[[Prevention (medical)|Secondary prevention]] of lung cancer consists of [[smoking cessation]] and [[Screening (medicine)|screening]]. Secondary chemoprevention focuses on blocking the development of lung cancer in individuals in whom a [[precancerous]] [[lesion]] has been detected.
-==References==
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-{{SIB}}
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+[[Category:Types of cancer]]
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-[[Category:Oncology]]
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