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| Lung cancer Classification & external resources | |
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| Cross section of a human lung. The white area in the upper lobe is cancer; the black areas indicate the patient was a smoker. | |
| ICD-10 | C33.-C34. |
| ICD-9 | 162 |
| DiseasesDB | 7616 |
| MedlinePlus | 007194 |
| eMedicine | med/1333 med/1336 emerg/335 radio/807 radio/405 radio/406 |
| MeSH | D002283 |
Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells. Lung cancer, the most common cause of cancer-related death in men and the second most common in women,[[World Health Organization|WHO]] (2004). Deaths by cause, sex and mortality stratum (PDF). World Health Organization. Retrieved on 2007-06-01.Lung Cancer Facts (Women). National Lung Cancer Partnership (2006). Retrieved on 2007-05-26. is responsible for 1.3 million deaths worldwide annually.[[World Health Organization|WHO]] (February 2006). Cancer. World Health Organization. Retrieved on 2007-06-25. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.Minna, JD (2004). Harrison\'s Principles of Internal Medicine. McGraw-Hill, 506–516. DOI:10.1036/0071402357. ISBN 0071391401.
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 surgery, while small cell lung carcinoma (SCLC) usually responds better to chemotherapy and radiation. The most common cause of lung cancer is long term exposure to 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 genetic factors,Gorlova, OY; Weng SF, Zhang Y et al. (July 2007). "Aggregation of cancer among relatives of never-smoking lung cancer patients". International Journal of Cancer 121 (1): 111–118. PMID 17304511. Hackshaw, AK; Law MR, Wald NJ (October 1997). "The accumulated evidence on lung cancer and environmental tobacco smoke". British Medical Journal 315 (7114): 980–988. PMID 9365295. Retrieved on 2007-08-10. radon gas, asbestos, and air pollution,Kabir, Z; Bennett K, Clancy L (February 2007). "Lung cancer and urban air-pollution in dublin: a temporal association?". Irish Medical Journal 100 (2): 367–369. PMID 17432813. Coyle, YM; Minahjuddin AT, Hynan LS, Minna JD (September 2006). "An ecological study of the association of metal air pollutants with lung cancer incidence in Texas.". Journal of Thoracic Oncology 1 (7): 654–661. PMID 17409932. Chiu, HF; Cheng MH, Tsai SS et al. (December 2006). "Outdoor air pollution and female lung cancer in Taiwan.". Inhalation Toxicology 18 (13): 1025–1031. PMID 16966302. including second-hand smoke.U.S. Department of Health and Human Services. "The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General", 2006; One of the major conclusions of the Surgeon General Report is: "Secondhand smoke exposure causes disease and premature death in children and adults who do not smoke."WHO International Agency for Research on Cancer "Tobacco Smoke and Involuntary Smoking" IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 83, 2002; the evaluation of the Monograph is: "There is sufficient evidence that involuntary smoking (exposure to secondhand or \'environmental\' tobacco smoke) causes lung cancer in humans. [...] Involuntary smoking (exposure to secondhand or \'environmental\' tobacco smoke) is carcinogenic to humans (Group 1)."
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. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient\'s performance status. Possible treatments include surgery, chemotherapy, and radiotherapy. With treatment, the five-year survival rate is 14%.
Contents |
| Histological type | Frequency (%) |
|---|---|
| Non-small cell lung carcinoma | 80.4 |
| Small cell lung carcinoma | 16.8 |
| CarcinoidMorandi, U; Casali C, Rossi G (2006). "Bronchial typical carcinoid tumors". Seminars in Thoracic and Cardiovascular Surgery 18 (3): 191–198. PMID 17185178. | 0.8 |
| SarcomaEtienne-Mastroianni, B; Falchero L, Chalabreysse L et al. (December 2002). "Primary sarcomas of the lung: a clinicopathologic study of 12 cases". Lung Cancer 38 (3): 283–289. PMID 12445750. | 0.1 |
| Unspecified lung cancer | 1.9 |
The vast majority of lung cancers are carcinomas—malignancies that arise from epithelial cells. There are two main types of lung carcinoma, categorized by the size and appearance of the malignant cells seen by a histopathologist under a microscope: non-small cell (80.4%) and small-cell (16.8%) lung carcinoma.Travis, WD; Travis LB, Devesa SS (January 1995). "Lung cancer". Cancer 75 (Suppl. 1): 191–202. PMID 8000996. This classification, based on histological criteria, has important implications for clinical management and prognosis of the disease.
The non-small cell lung carcinomas are grouped together because their prognosis and management are similar. There are three main sub-types: squamous cell lung carcinoma, adenocarcinoma and large cell lung carcinoma.
| Histological sub-type | Frequency of all lung cancers (%) | |
|---|---|---|
| Squamous cell lung carcinoma | 31.1 | |
| Adenocarcinoma | Adenocarcinoma (not otherwise specified) | 23.2 |
| Bronchioloalveolar carcinoma | 3.0 | |
| Adenosquamous carcinoma | 1.2 | |
| Papillary adenocarcinoma | 0.7 | |
| Mucoepidermoid carcinomaSánchez-Mora, N; Parra-Blanco V, Cebollero-Presmanes M et al. (January 2007). "Mucoepidermoid tumors of the bronchus. Ultrastructural and immunohistochemical study". Histology and Histopathology 22 (1): 9–13. PMID 17128406. | 0.1 | |
| Adenoid cystic carcinomaMoran, CA; Suster S, Koss MN (March 1994). "Primary adenoid cystic carcinoma of the lung. A clinicopathologic and immunohistochemical study of 16 cases". Cancer 73 (5): 1390–1397. PMID 7509254. | 0.04 | |
| Other specified adenocarcinoma | 1.1 | |
| Large cell carcinoma | 10.7 | |
| Giant cell and spindle cell carcinoma | 0.4 | |
| Other/unspecified non-small cell lung carcinoma | 8.9 | |
Accounting for 31.1% of lung cancers, squamous cell lung carcinoma usually starts near a central bronchus. Cavitation and necrosis within the center of the cancer is a common finding. Well-differentiated squamous cell lung cancers often grow more slowly than other cancer types.Vaporciyan, AA; Nesbitt JC, Lee JS et al. (2000). Cancer Medicine. B C Decker Inc., 1227–1292. ISBN 1-55009-113-1.
Adenocarcinoma accounts for 29.4% of lung cancers. It usually originates in peripheral lung tissue. Most cases of adenocarcinoma are associated with smoking. However, among people who have never smoked ("never-smokers"), adenocarcinoma is the most common form of lung cancer.Subramanian, J; Govindan R (February 2007). "Lung cancer in never smokers: a review". Journal of Clinical Oncology 25 (5): 561–570. American Society of Clinical Oncology. PMID 17290066. A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have different responses to treatment.Raz, DJ; He B, Rosell R, Jablons DM (March 2006). "Bronchioloalveolar carcinoma: a review". Clinical Lung Cancer 7 (5): 313–322. Cancer Information Group. PMID 16640802.
Accounting for 10.7% of lung cancers, large cell lung carcinoma is a fast-growing form that develops near the surface of the lung.Veronesi G; Morandi U, Alloisio M et al. (July 2006). "Large cell neuroendocrine carcinoma of the lung: a retrospective analysis of 144 surgical cases". Lung Cancer 53 (1): 111–115. doi:10.1016/j.lungcan.2006.03.007. PMID 16697073. It is often poorly differentiated and tends to metastasize early.
 by core needle biopsy.jpg/58px-Lung small cell carcinoma (1) by core needle biopsy.jpg)
Small cell lung carcinoma (microscopic view of a core needle biopsy)
Small cell lung carcinoma (SCLC, also called "oat cell carcinoma") is less common. It tends to arise in the larger airways (primary and secondary bronchi) and grows rapidly, becoming quite large. The "oat" cell contains dense neurosecretory granules (vesicles containing neuroendocrine hormones) which give this an endocrine/paraneoplastic syndrome association.Rosti, G; Bevilacqua G, Bidoli P et al. (March 2006). "Small cell lung cancer". Annals of Oncology 17 (Suppl. 2): 5–10. doi:10.1093/annonc/mdj910. PMID 16608983. Retrieved on 2007-09-06. While initially more sensitive to chemotherapy, it ultimately carries a worse prognosis and is often metastatic at presentation. Small cell lung cancers are divided into Limited stage and Extensive stage disease. This type of lung cancer is strongly associated with smoking.Barbone, F; Bovenzi M, Cavallieri F, Stanta G (December 1997). "Cigarette smoking and histologic type of lung cancer in men" (PDF). Chest 112 (6): 1474–1479. American College of Chest Physicians. PMID 9404741. Retrieved on 2007-09-07.
The lung is a common place for metastasis from tumors in other parts of the body. These cancers are identified by the site of origin, thus a breast cancer metastasis to the lung is still known as breast cancer. They often have a characteristic round appearance on chest x-ray.Seo, JB; Im JG, Goo JM et al. (2001). "Atypical pulmonary metastases: spectrum of radiologic findings". Radiographics 21 (2): 403–417. PMID 11259704. Retrieved on 2007-09-10. Primary lung cancers themselves most commonly metastasize to the adrenal glands, liver, brain, and bone.
Lung cancer staging is an assessment of the degree of spread of the cancer from its original source. It is an important factor affecting the prognosis and potential treatment of lung cancer. Non-small cell lung carcinoma is staged from IA ("one A", best prognosis) to IV ("four", worst prognosis).Mountain, CF; Libshitz HI, Hermes KE (2003). A Handbook for Staging, Imaging, and Lymph Node Classification. Charles P Young Company. Retrieved on 2007-09-01. Small cell lung carcinoma is classified as limited stage if it is confined to one half of the chest and within the scope of a single radiotherapy field. Otherwise it is extensive stage.Collins, LG; Haines C, Perkel R, Enck RE (January 2007). "Lung cancer: diagnosis and management". American Family Physician 75 (1): 56–63. American Academy of Family Physicians. PMID 17225705. Retrieved on 2007-08-10.
Symptoms that suggest lung cancer include:Hamilton, W; Peters TJ, Round A, Sharp D (December 2005). "What are the clinical features of lung cancer before the diagnosis is made? A population based case-control study". Thorax 60 (12): 1059–1065. BMJ Publishing Group Ltd.. PMID 16227326.
If the cancer grows in the airway, it may obstruct airflow, causing breathing difficulties. This can lead to accumulation of secretions behind the blockage, predisposing the patient to pneumonia. Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed up.
Depending on the type of tumor, so-called paraneoplastic phenomena may initially attract attention to the disease.Honnorat, J; Antoine JC (May 2007). "Paraneoplastic neurological syndromes". Orphanet Journal of Rare Diseases 2: 22. BioMed Central Ltd.. doi:10.1186/1750-1172-2-22. PMID 17480225. Retrieved on 2007-09-05. In lung cancer, these phenomena may include Lambert-Eaton myasthenic syndrome (muscle weakness due to auto-antibodies), hypercalcemia or syndrome of inappropriate antidiuretic hormone (SIADH). Tumors in the top (apex) of the lung, known as Pancoast tumors,Jones, DR; Detterbeck FC (July 1998). "Pancoast tumors of the lung". Current Opinion in Pulmonary Medicine 4 (4): 191–197. PMID 10813231. may invade the local part of the sympathetic nervous system, leading to changed sweating patterns and eye muscle problems (a combination known as Horner\'s syndrome), as well as muscle weakness in the hands due to invasion of the brachial plexus.
Many of the symptoms of lung cancer (bone pain, fever, weight loss) are nonspecific; in the elderly, these may be attributed to comorbid illness. In many patients, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention. Common sites of metastasis include the bone, such as the spine (causing back pain and occasionally spinal cord compression), the liver and the brain. About 10% of people with lung cancer do not have symptoms at diagnosis; these cancers are incidentally found on routine chest x-rays.
The main causes of lung cancer (and cancer in general) include carcinogens (such as those in tobacco smoke), ionizing radiation, and viral infection.This exposure causes cumulative changes to the DNA in the tissue lining the bronchi of the lungs (the bronchial epithelium).As more tissue becomes damaged, eventually a cancer develops.
The incidence of lung cancer is highly correlated with smoking. Source: NIH.
Smoking, particularly of cigarettes, is by far the main contributor to lung cancer. In the United States, smoking is estimated to account for 87% of lung cancer cases (90% in men and 85% in women).Samet, JM; Wiggins CL, Humble CG, Pathak DR (May 1988). "Cigarette smoking and lung cancer in New Mexico". American Review of Respiratory Disease 137 (5): 1110–1113. PMID 3264122. Among male smokers, the lifetime risk of developing lung cancer is 17.2%. Among female smokers, the risk is 11.6%. This risk is significantly lower in non-smokers: 1.3% in men and 1.4% in women.Villeneuve, PJ; Mao Y (November 1994). "Lifetime probability of developing lung cancer, by smoking status, Canada". Canadian Journal of Public Health 85 (6): 385–388. PMID 7895211. Cigarette smoke contains over 60 known carcinogensHecht, S (October 2003). "Tobacco carcinogens, their biomarkers and tobacco-induced cancer". Nature Reviews. Cancer 3 (10): 733–744. Nature Publishing Group. doi:10.1038/nrc1190. PMID 14570033. Retrieved on 2007-08-10. including radioisotopes from the radon decay sequence, nitrosamine, and benzopyrene. Additionally, nicotine appears to depress the immune response to malignant growths in exposed tissue. The length of time a person smokes as well as the amount smoked increases the person\'s chance of developing lung cancer. If a person stops smoking, this chance steadily decreases as damage to the lungs is repaired and contaminant particles are gradually removed.US Department of Health and Human Services (1990), The Health Benefits of Smoking Cessation: a Report of the Surgeon General, Centers for Disease Control (CDC), Office on Smoking and Health., pp. vi, 130, 148, 152, 155, 164, 166, <http://profiles.nlm.nih.gov/NN/B/B/C/T/_/nnbbct.pdf>. Retrieved on 18 November 2007 Across the developed world, almost 90% of lung cancer deaths are caused by smoking.Peto R, R; Lopez AD, Boreham J et al. (2006). Mortality from smoking in developed countries 1950–2000: Indirect estimates from National Vital Statistics. Oxford University Press. ISBN 0-19-262535-7. Retrieved on 2007-08-10. In addition, there is evidence that lung cancer in never-smokers has a better prognosis than in smokers,Nordquist, LT; Simon GR, Cantor A et al. (August 2004). "Improved survival in never-smokers vs current smokers with primary adenocarcinoma of the lung". Chest 126 (2): 347–351. American College of Chest Physicians. PMID 15302716. Retrieved on 2007-08-10. and that patients who smoke at the time of diagnosis have shorter survival than those who have quit.Tammemagi, CM; Neslund-Dudas C, Simoff M, Kvale P (January 2004). "Smoking and lung cancer survival: the role of comorbidity and treatment". Chest 125 (1): 27–37. American College of Chest Physicians. PMID 14718417. Retrieved on 2007-08-10.
Passive smoking—the inhalation of smoke from another\'s smoking—is a cause of lung cancer in non-smokers. Studies from the U.S.,CDC (December 1986). 1986 Surgeon General\'s report: the health consequences of involuntary smoking. CDC. Retrieved on 2007-08-10.
* National Research Council (1986). Environmental tobacco smoke: measuring exposures and assessing health effects. National Academy Press. ISBN 0-309-07456-8.
* EPA (1992). "Respiratory health effects of passive smoking: lung cancer and other disorders". EPA. Retrieved on 2007-08-10.
* California Environmental Protection Agency (1997). "Health effects of exposure to environmental tobacco smoke". Tobacco Control 6 (4): 346–353. PMID 9583639. Retrieved on 2007-08-10.
* CDC (December 2001). "State-specific prevalence of current cigarette smoking among adults, and policies and attitudes about secondhand smoke—United States, 2000". Morbidity and Mortality Weekly Report 50 (49): 1101–1106. CDC. PMID 11794619. Retrieved on 2007-08-10.
* Alberg, AJ; Samet JM (January 2003). "Epidemiology of lung cancer". Chest 123 (S1): 21S-49S. American College of Chest Physicians. PMID 12527563. Retrieved on 2007-08-10. Europe,Boffetta, P; Agudo A, Ahrens W et al. (October 1998). "Multicenter case-control study of exposure to environmental tobacco smoke and lung cancer in Europe". Journal of the National Cancer Institute 90 (19): 1440–1450. Oxford University Press. PMID 9776409. Retrieved on 2007-08-10. the UK,Report of the Scientific Committee on Tobacco and Health. Department of Health (March 1998). Retrieved on 2007-07-09.
* Hackshaw, AK (June 1998). "Lung cancer and passive smoking". Statistical Methods in Medical Research 7 (2): 119–136. PMID 9654638. and AustraliaNational Health and Medical Research Council (April 1994). "The health effects and regulation of passive smoking". Australian Government Publishing Service. Retrieved on 2007-08-10. have consistently shown a significant increase in relative risk among those exposed to passive smoke. Recent investigation of sidestream smoke suggests it is more dangerous than direct smoke inhalation.Schick, S; Glantz S (December 2005). "Philip Morris toxicological experiments with fresh sidestream smoke: more toxic than mainstream smoke". Tobacco Control 14 (6): 396–404. PMID 16319363.
Radon is a colorless and odorless gas generated by the breakdown of radioactive radium, which in turn is the decay product of uranium, found in the earth\'s crust. The radiation decay products ionize genetic material, causing mutations that sometimes turn cancerous. Radon exposure is the second major cause of lung cancer after smoking.Catelinois, O; Rogel A, Laurier D et al. (May 2006). "Lung Cancer Attributable to Indoor Radon Exposure in France: Impact of the Risk Models and Uncertainty Analysis". Environmental Health Perspectives 114 (9): 1361–1366. National Institute of Environmental Health Science. doi:10.1289/ehp.9070. PMID 16966089. Retrieved on 2007-08-10. Radon gas levels vary by locality and the composition of the underlying soil and rocks. For example, in areas such as Cornwall in the UK (which has granite as substrata), radon gas is a major problem, and buildings have to be force-ventilated with fans to lower radon gas concentrations. The United States Environmental Protection Agency (EPA) estimates that one in 15 homes in the U.S. has radon levels above the recommended guideline of 4 picocuries per liter (pCi/L) (148 Bq/m³).EPA (October 2006). Radiation information: radon. EPA. Retrieved on 2007-08-11. Iowa has the highest average radon concentration in the United States; studies performed there have demonstrated a 50% increased lung cancer risk with prolonged radon exposure above the EPA\'s action level of 4 pCi/L.Field, RW; Steck DJ, Smith BJ et al. (June 2000). "Residential radon gas exposure and lung cancer: the Iowa Radon Lung Cancer Study". American Journal of Epidemiology 151 (11): 1091–1102. Oxford Journals. PMID 10873134. Retrieved on 2007-08-11. EPA (June 2000). Iowa Radon Lung Cancer Study. EPA. Retrieved on 2007-08-11.
Asbestos can cause a variety of lung diseases, including lung cancer. There is a synergistic effect between tobacco smoking and asbestos in the formation of lung cancer.O\'Reilly, KM; Mclaughlin AM, Beckett WS, Sime PJ (March 2007). "Asbestos-related lung disease". American Family Physician 75 (5): 683–688. PMID 17375514. Retrieved on 2007-08-18. In the UK, asbestos accounts for 2–3% of male lung cancer deaths.Darnton, AJ; McElvenny DM, Hodgson JT (January 2006). "Estimating the number of asbestos-related lung cancer deaths in Great Britain from 1980 to 2000". Annals of Occupational Hygiene 50 (1): 29–38. PMID 16126764. Retrieved on 2007-09-07. Asbestos can also cause cancer of the pleura, called mesothelioma (which is different from lung cancer).
Viruses are known to cause lung cancer in animalsLeroux, C; Girard N, Cottin V et al. (Mar-April 2007). "Jaagsiekte Sheep Retrovirus (JSRV): from virus to lung cancer in sheep". Veterinary Research 38 (2): 211–228. PMID 17257570. Palmarini, M; Fan H (November 2001). "Retrovirus-induced ovine pulmonary adenocarcinoma, an animal model for lung cancer". Journal of the National Cancer Institute 93 (21): 1603–1614. Oxford University Press. PMID 11698564. Retrieved on 2007-08-11. and recent evidence suggests similar potential in humans. Implicated viruses include human papillomavirus,Cheng, YW; Chiou HL, Sheu GT et al. (April 2001). "The association of human papillomavirus 16/18 infection with lung cancer among nonsmoking Taiwanese women". Cancer Research 61 (7): 2799–2803. American Association for Cancer Research. PMID 11306446. Retrieved on 2007-08-11. JC virus,Zheng, H; Aziz HA, Nakanishi Y et al. (May 2007). "Oncogenic role of JC virus in lung cancer". Journal of Pathology 212 (3): 306–315. PMID 17534844. simian virus 40 (SV40), BK virus and cytomegalovirus.Giuliani, L; Jaxmar T, Casadio C et al. (September 2007). "Detection of oncogenic viruses (SV40, BKV, JCV, HCMV, HPV) and p53 codon 72 polymorphism in lung carcinoma". Lung Cancer 57 (3): 273–281. PMID 17400331. These viruses may affect the cell cycle and inhibit apoptosis, allowing uncontrolled cell division.
Similar to many other cancers, lung cancer is initiated by activation of oncogenes or inactivation of tumor suppressor genes.Fong, KM; Sekido Y, Gazdar AF, Minna JD (October 2003). "Lung cancer. 9: Molecular biology of lung cancer: clinical implications". Thorax 58 (10): 892–900. BMJ Publishing Group Ltd.. PMID 14514947. Oncogenes are genes that are believed to make people more susceptible to cancer. Proto-oncogenes are believed to turn into oncogenes when exposed to particular carcinogens.Salgia, R; Skarin AT (March 1998). "Molecular abnormalities in lung cancer". Journal of Clinical Oncology 16 (3): 1207–1217. PMID 9508209. Mutations in the K-ras proto-oncogene are responsible for 20–30% of non-small cell lung cancers.Aviel-Ronen, S; Blackhall FH, Shepherd FA, Tsao MS (July 2006). "K-ras mutations in non-small-cell lung carcinoma: a review". Clinical Lung Cancer 8 (1): 30–38. Cancer Information Group. PMID 16870043. Chromosomal damage can lead to loss of heterozygosity. This can cause inactivation of tumor suppressor genes. Damage to chromosomes 3p, 5q, 13q and 17p are particularly common in small cell lung carcinoma. The TP53 tumor suppressor gene, located on chromosome 17p, is often affected.Devereux, TR; Taylor JA, Barrett JC (March 1996). "Molecular mechanisms of lung cancer. Interaction of environmental and genetic factors". Chest 109 (Suppl. 3): 14S-19S. American College of Chest Physicians. PMID 8598134. Retrieved on 2007-08-11.
Several genetic polymorphisms are associated with lung cancer. These include polymorphisms in genes coding for interleukin-1,Engels, EA; Wu X, Gu J et al. (July 2007). "Systematic evaluation of genetic variants in the inflammation pathway and risk of lung cancer". Cancer Research 67 (13): 6520–6527. American Association for Cancer Research. PMID 17596594. cytochrome P450,Wenzlaff, AS; Cote ML, Bock CH et al. (December 2005). "CYP1A1 and CYP1B1 polymorphisms and risk of lung cancer among never smokers: a population-based study". Carcinogenesis 26 (12): 2207–2212. Oxford University Press. PMID 16051642. apoptosis promoters such as caspase-8,Son, JW; Kang HK, Chae MH et al. (September 2006). "Polymorphisms in the caspase-8 gene and the risk of lung cancer". Cancer Genetics and Cytogenetics 169 (2): 121–127. PMID 16938569. and DNA repair molecules such as XRCC1.Yin, J; Vogel U, Ma Y et al. (May 2007). "The DNA repair gene XRCC1 and genetic susceptibility of lung cancer in a northeastern Chinese population". Lung Cancer 56 (2): 153–160. PMID 17316890. People with these polymorphisms are more likely to develop lung cancer after exposure to carcinogens.
Chest x-ray showing a cancerous tumor in the left lung
Performing a chest x-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. This may reveal an obvious mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (pneumonia), or pleural effusion. If there are no x-ray findings but the suspicion is high (such as a heavy smoker with blood-stained sputum), bronchoscopy and/or a CT scan may provide the necessary information. Bronchoscopy or CT-guided biopsy is often used to identify the tumor type.
CT scan showing a cancerous tumor in the left lung
The differential diagnosis for patients who present with abnormalities on chest x-ray includes lung cancer, as well as nonmalignant diseases. These include infectious causes such as tuberculosis or pneumonia, or inflammatory conditions such as sarcoidosis. These diseases can result in mediastinal lymphadenopathy or lung nodules, and sometimes mimic lung cancers.
Prevention is the most cost-effective means of fighting lung cancer. While in most countries industrial and domestic carcinogens have been identified and banned, tobacco smoking is still widespread. Eliminating tobacco smoking is a primary goal in the prevention of lung cancer, and smoking cessation is an important preventative tool in this process.Vineis, P; Hoek G, Krzyzanowski M et al. (February 2007). "Lung cancers attributable to environmental tobacco smoke and air pollution in non-smokers in different European countries: a prospective study". Environmental Health 6: 7. BioMed Central. doi:10.1186/1476-069X-6-7. PMID 17302981. Retrieved on 2007-08-11.
Policy interventions to decrease passive smoking in public areas such as restaurants and workplaces have become more common in many Western countries, with California taking a lead in banning smoking in public establishments in 1998. Ireland played a similar role in Europe in 2004, followed by Italy and Norway in 2005, Scotland as well as several others in 2006, England in 2007, and France in 2008. New Zealand has banned smoking in public places as of 2004.
The state of Bhutan has had a complete smoking ban since 2005.Pandey, G (February 2005). Bhutan\'s smokers face public ban. BBC. Retrieved on 2007-09-07. In many countries, pressure groups are campaigning for similar bans. Arguments cited against such bans are criminalisation of smoking, increased risk of smuggling and the risk that such a ban cannot be enforced.Gray, N (February 2003). "A global approach to tobacco policy". Lung Cancer 39 (2): 113–117. BioMed Central. PMID 12581561.
A 2008 study performed in over 75,000 middle-aged and elderly people demonstrated that the long-term use of supplemental multivitamins, such as vitamin C, vitamin E, and folate did not reduce the risk of lung cancer. To the contrary, the study indicates that the long term intake of high doses of vitamin E supplements may even increase the risk of lung cancer.Slatore CG, Littman AJ, Au DH, Satia JA, White E (2008). "Long-term use of supplemental multivitamins, vitamin C, vitamin E, and folate does not reduce the risk of lung cancer". Am. J. Respir. Crit. Care Med. 177 (5): 524–30. doi:10.1164/rccm.200709-1398OC. PMID 17989343.
Screening refers to the use of medical tests to detect disease in asymptomatic people. Possible screening tests for lung cancer include chest x-ray or computed tomography (CT) of the chest. So far, screening programs for lung cancer have not demonstrated any clear benefit. Randomized controlled trials are underway in this area to see if decreased long-term mortality can be directly observed from CT screening.Gohagan, JK; Marcus PM, Fagerstrom RM et al. (January 2005). "Final results of the Lung Screening Study, a randomized feasibility study of spiral CT versus chest X-ray screening for lung cancer". Lung Cancer 47 (1): 9–15. doi:10.1016/j.lungcan.2004.06.007. PMID 15603850.
Treatment for lung cancer depends on the cancer\'s specific cell type, how far it has spread, and the patient\'s performance status. Common treatments include surgery, chemotherapy, and radiation therapy.
If investigations confirm lung cancer, CT scan and often positron emission tomography (PET) are used to determine whether the disease is localised and amenable to surgery or whether it has spread to the point where it cannot be cured surgically.
Blood tests and spirometry (lung function testing) are also necessary to assess whether the patient is well enough to be operated on. If spirometry reveals poor respiratory reserve (often due to chronic obstructive pulmonary disease), surgery may be contraindicated.
Surgery itself has an operative death rate of about 4.4%, depending on the patient\'s lung function and other risk factors.Strand, TE; Rostad H, Damhuis RA, Norstein J (June 2007). "Risk factors for 30-day mortality after resection of lung cancer and prediction of their magnitude". Thorax. BMJ Publishing Group Ltd.. PMID 17573442. Surgery is usually only an option in non-small cell lung carcinoma limited to one lung, up to stage IIIA. This is assessed with medical imaging (computed tomography, positron emission tomography). A sufficient pre-operative respiratory reserve must be present to allow adequate lung function after the tissue is removed.
Procedures include wedge resection (removal of part of a lobe), segmentectomy (removal of an anatomic division of a particular lobe of the lung), lobectomy (one lobe), bilobectomy (two lobes) or pneumonectomy (whole lung). In patients with adequate respiratory reserve, lobectomy is the preferred option, as this minimizes the chance of local recurrence. If the patient does not have enough functional lung for this, wedge resection may be performed.El-Sherif, A; Gooding WE, Santos R et al. (August 2006). "Outcomes of sublobar resection versus lobectomy for stage I non-small cell lung cancer: a 13-year analysis". Annals of Thoracic Surgery 82 (2): 408–415. PMID 16863738. Radioactive iodine brachytherapy at the margins of wedge excision may reduce recurrence to that of lobectomy.Fernando, HC; Santos RS, Benfield JR et al. (February 2005). "Lobar and sublobar resection with and without brachytherapy for small stage IA non-small cell lung cancer". Journal of Thoracic and Cardiovascular Surgery 129 (2): 261–267. PMID 15678034.
Small cell lung carcinoma is treated primarily with chemotherapy and radiation, as surgery has no demonstrable influence on survival. Primary chemotherapy is also given in metastatic non-small cell lung carcinoma.
The combination regimen depends on the tumor type. Non-small cell lung carcinoma is often treated with cisplatin or carboplatin, in combination with gemcitabine, paclitaxel, docetaxel, etoposide or vinorelbine.Clegg, A; Scott DA, Hewitson P et al. (January 2002). "Clinical and cost effectiveness of paclitaxel, docetaxel, gemcitabine, and vinorelbine in non-small cell lung cancer: a systematic review". Thorax 57 (1): 20–28. BMJ Publishing Group Ltd. PMID 11809985. In small cell lung carcinoma, cisplatin and etoposide are most commonly used.Murray, N; Turrisi AT (March 2006). "A review of first-line treatment for small-cell lung cancer". Journal of Thoracic Oncology 1 (3): 270–278. PMID 17409868. Combinations with carboplatin, gemcitabine, paclitaxel, vinorelbine, topotecan and irinotecan are also used.Azim, HA; Ganti AK (March 2007). "Treatment options for relapsed small-cell lung cancer". Anticancer drugs 18 (3): 255–261. PMID 17264756. MacCallum, C; Gillenwater HH (July 2006). "Second-line treatment of small-cell lung cancer". Current Oncology Reports 8 (4): 258–264. PMID 17254525.
Adjuvant chemotherapy refers to the use of chemotherapy after surgery to improve the outcome. During surgery, samples are taken from the lymph nodes. If these samples contain cancer, then the patient has stage II or III disease. In this situation, adjuvant chemotherapy may improve survival by up to 15%.Winton, T; Livingston R, Johnson D et al. (June 2005
