Avoidance of risk factors, including smoking and air pollution, is the primary method of prevention. Treatment and long-term outcomes depend on the type of cancer, the stage (degree of spread), and the person's overall health. Most cases are not curable. Common treatments include surgery, chemotherapy, and radiotherapy. NSCLC is sometimes treated with surgery, whereas SCLC usually responds better to chemotherapy and radiotherapy.
Worldwide in 2012, lung cancer occurred in 1.8 million people and resulted in 1.6 million deaths. This makes it the most common cause of cancer-related death in men and second most common in women after breast cancer. The most common age at diagnosis is 70 years. In the United States, five-year survival rate is 19.4%, while in Japan it is 41.4%. Outcomes on average are worse in the developing world.
Signs and symptoms
Signs and symptoms which may suggest lung cancer include:
If the cancer grows in the airways, it may obstruct airflow, causing breathing difficulties. The obstruction can also lead to accumulation of secretions behind the blockage, and increase the risk of pneumonia.
Many of the symptoms of lung cancer (poor appetite, weight loss, fever, fatigue) are not specific. In many people, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention. Symptoms that suggest the presence of metastatic disease include weight loss, bone pain, and neurological symptoms (headaches, fainting, convulsions, or limb weakness). Common sites of spread include the brain, bone, adrenal glands, opposite lung, liver, pericardium, and kidneys. About 10% of people with lung cancer do not have symptoms at diagnosis; these cancers are incidentally found on routine chest radiography.
Relationship between cigarette consumption per person (blue) and male lung cancer rates (dark yellow) in the US over the century.
Risk of death from lung cancer is strongly correlated with smoking
Passive smoking - the inhalation of smoke from another's smoking - is a cause of lung cancer in nonsmokers. A passive smoker can be defined as someone either living or working with a smoker. Studies from the US, the UK and other European countries have consistently shown a significantly-increased risk among those exposed to passive smoking. Those who live with someone who smokes have a 20-30% increase in risk while those who work in an environment with secondhand smoke have a 16-19% increase in risk. Investigations of sidestream smoke suggest that it is more dangerous than direct smoke. Passive smoking results in roughly 3,400 lung cancer-related deaths each year in the US.
Marijuana smoke contains many of the same carcinogens as those found in tobacco smoke, however, the effect of smoking cannabis on lung cancer risk is not clear. A 2013 review did not find an increased risk from light to moderate use. A 2014 review found that smoking cannabis doubled the risk of lung cancer, though cannabis is in many countries commonly mixed with tobacco.
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 become cancerous. Radon is the second most-common cause of lung cancer in the US, causing about 21,000 deaths each year. The risk increases 8-16% for every 100 Bq/m³ increase in the radon concentration. Radon gas levels vary by locality and the composition of the underlying soil and rocks. About one in 15 homes in the US have radon levels above the recommended guideline of 4 picocuries per liter (pCi/l) (148 Bq/m³).
Asbestos can cause a variety of lung diseases such as lung cancer. Tobacco smoking and asbestos both have synergistic effects on the development of lung cancer. In smokers who work with asbestos, the risk of lung cancer is increased 45-fold compared to the general population. Asbestos can also cause cancer of the pleura, called mesothelioma - which actually is different from lung cancer.
Tentative evidence supports an increased risk of lung cancer from indoor air pollution in relation to the burning of wood, charcoal, dung, or crop residue for cooking and heating. Women who are exposed to indoor coal smoke have roughly twice the risk, and many of the by-products of burning biomass are known or suspected carcinogens. This risk affects about 2.4 billion people worldwide, and it is believed to result in 1.5% of lung cancer deaths.
Numerous other substances, occupations, and environmental exposures have been linked to lung cancer. The International Agency for Research on Cancer (IARC) states that there is some "sufficient evidence" to show that the following are carcinogenic in the lungs:
There is a small increase in the risk of lung cancer in people affected by systemic sclerosis.
Similar to many other cancers, lung cancer is initiated by either the activation of oncogenes or the inactivation of tumor suppressor genes. Carcinogens cause mutations in these genes that induce the development of cancer.
Clinical practice guidelines recommend frequencies for pulmonary nodule surveillance. CT imaging should not be used for longer or more frequently than indicated, as the extended surveillance exposes people to increased radiation and is costly.
Pie chart showing incidences of non-small cell lung cancers as compared to small cell carcinoma shown at right, with fractions of smokers versus non-smokers shown for each type.
Age-adjusted incidence of lung cancer by histological type
Nearly 40% of lung cancers are adenocarcinoma, which usually comes from peripheral lung tissue. Although most cases of adenocarcinoma are associated with smoking, adenocarcinoma is also the most-common form of lung cancer among people who have smoked fewer than 100 cigarettes in their lifetimes ("never-smokers") and ex-smokers with a modest smoking history. A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have a better long-term survival.
Squamous-cell carcinoma causes about 30% of lung cancers. They typically occur close to large airways. A hollow cavity and associated cell death are commonly found at the center of the tumor.
About 10 to 15% of lung cancers are large-cell carcinoma. These are so named because the cancer cells are large, with excess cytoplasm, large nuclei, and conspicuous nucleoli.
Small-cell lung carcinoma
Small-cell lung carcinoma (microscopic view of a core needle biopsy)
In SCLC, the cells contain dense neurosecretory granules (vesicles containing neuroendocrinehormones), which give this tumor an endocrine or paraneoplastic syndrome association. Most cases arise in the larger airways (primary and secondary bronchi). Sixty to seventy percent have extensive disease (which cannot be targeted within a single radiation therapy field) at presentation.
The lungs are a common place for the spread of tumors from other parts of the body. Secondary cancers are classified by the site of origin; for example, breast cancer that has been spread to the lung is called metastatic breast cancer. Metastases often have a characteristic round appearance on chest radiograph.
Lung cancer staging is an assessment of the degree of spread of the cancer from its original source. It is one of the factors affecting both the prognosis and the potential treatment of lung cancer.
The evaluation of non-small-cell lung carcinoma (NSCLC) staging uses the TNM classification (tumor, node, metastasis). This is based on the size of the primary tumor, lymph node involvement, and distant metastasis.
Using the TNM descriptors, a group is assigned, ranging from occult cancer, through stages 0, IA (one-A), IB, IIA, IIB, IIIA, IIIB, and IV (four). This stage group assists with the choice of treatment and estimation of prognosis.
Stage group according to TNM classification in lung cancer
T1a-T1b N0 M0
T2a N0 M0
T1a-T2a N1 M0
T2b N0 M0
T2b N1 M0
T3 N0 M0
T1a-T3 N2 M0
T3 N1 M0
T4 N0-N1 M0
T4 N2 M0
SCLC has traditionally been classified as "limited stage" (confined to one-half of the chest and within the scope of a single tolerable radiotherapy field) or "extensive stage" (more widespread disease). However, the TNM classification and grouping are useful in estimating prognosis.
For both NSCLC and SCLC, the two general types of staging evaluations are clinical staging and surgical staging. Clinical staging is performed before definitive surgery. It is based on the results of imaging studies (such as CT scans and PET scans) and biopsy results. Surgical staging is evaluated either during or after the operation. It is based on the combined results of surgical and clinical findings, including surgical sampling of thoracic lymph nodes.
Diagrams of main features of staging
Stage IA and IB lung cancer
Stage IIA lung cancer
Stage IIB lung cancer
One option for stage IIB lung cancer, with T2b; but if tumor is within 2 cm of the carina, this is stage 3
Stage IIIA lung cancer
Stage IIIA lung cancer, if there is one feature from the list on each side
Stage IIIA lung cancer
Stage IIIB lung cancer
Stage IIIB lung cancer
Stage IV lung cancer
Cross section of a human lung: The white area in the upper lobe is cancer; the black areas are discoloration due to smoking.
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 preventive tool in this process.
Policy interventions to decrease passive smoking in public areas such as restaurants and workplaces have become more common in many Western countries.Bhutan has had a complete smoking ban since 2005 while India introduced a ban on smoking in public in October 2008. The World Health Organization has called for governments to institute a total ban on tobacco advertising to prevent young people from taking up smoking. They assess that such bans have reduced tobacco consumption by 16% where instituted.
Cancer screening uses medical tests to detect disease in large groups of people who have no symptoms. For individuals with high risk of developing lung cancer, computed tomography (CT) screening can detect cancer and give a person options to respond to it in a way that prolongs life. This form of screening reduces the chance of death from lung cancer by an absolute amount of 0.3% (relative amount of 20%). High risk people are those age 55-74 who have smoked equivalent amount of a pack of cigarettes daily for 30 years including time within the past 15 years.
The United States Preventive Services Task Force (USPSTF) recommends yearly screening using low-dose computed tomography in those who have a total smoking history of 30 pack-years and are between 55 and 80 years old until a person has not been smoking for more than 15 years. Screening should not be done in those with other health problems that would make treatment of lung cancer if found not an option. The English National Health Service was in 2014 re-examining the evidence for screening.
Some studies suggest that people who eat diets with a higher proportion of vegetables and fruit tend to have a lower risk, but this may be due to confounding--with the lower risk actually due to the association of a high fruit and vegetables diet with less smoking. Several rigorous studies have not demonstrated a clear association between diet and lung cancer risk, although meta-analysis that accounts for smoking status may show benefit from a healthy diet.
Treatment for lung cancer depends on the cancer's specific cell type, how far it has spread, and the person's performance status. Common treatments include palliative care,surgery, chemotherapy, and radiation therapy.Targeted therapy of lung cancer is growing in importance for advanced lung cancer. People who have lung cancer should be encouraged to stop smoking. There is no clear evidence which smoking cessation program is most effective for people who have been diagnosed with lung cancer. It is unclear if exercise training is beneficial for people who have advanced lung cancer. Exercise training may benefit people with NSCLC who are recovering from lung surgery. In addition, exercise training can benefit people with NSCLC who have received radiotherapy, chemotherapy, chemoradiotherapy, or palliative care.
Exercise training before lung cancer surgery improves outcomes. A home-based component in rehabilitation is also useful. Even though it is uncertain if home-based prehabilitation leads to less adverse events or hospitalization time, rehabilitation with a home-based component may improve recovery after treatment and overall lung health.
In most cases of early-stage NSCLC, removal of a lobe of lung (lobectomy) is the surgical treatment of choice. In people who are unfit for a full lobectomy, a smaller sublobar excision (wedge resection) may be performed. However, wedge resection has a higher risk of recurrence than lobectomy. Radioactive iodinebrachytherapy at the margins of wedge excision may reduce the risk of recurrence. Rarely, removal of a whole lung (pneumonectomy) is performed.Video-assisted thoracoscopic surgery (VATS) and VATS lobectomy use a minimally invasive approach to lung cancer surgery. VATS lobectomy is equally effective compared to conventional open lobectomy, with less postoperative illness.
In SCLC, chemotherapy and/or radiotherapy is typically used. However the role of surgery in SCLC is being reconsidered. Surgery might improve outcomes when added to chemotherapy and radiation in early stage SCLC.
The effectiveness of lung cancer surgery (resection) for people with stage I - IIA NSCLC is not clear, however, weak evidence suggests that a combined approach of lung cancer resection and removing the mediastinal lymph nodes (mediastinal lymph node dissection) may improve survival compared to lung resection and a sample of mediastinal nodes (not a complete node dissection).
Internal radiotherapy for lung cancer given via the airway.
Radiotherapy is often given together with chemotherapy, and may be used with curative intent in people with NSCLC who are not eligible for surgery. This form of high-intensity radiotherapy is called radical radiotherapy. A refinement of this technique is continuous hyperfractionated accelerated radiotherapy (CHART), in which a high dose of radiotherapy is given in a short time period. Radiosurgery refers to the radiotherapy technique of giving a precise high-dose of radiotherapy that is guided by a computer. Postoperative (adjuvant) thoracic radiotherapy generally should not be used after curative-intent surgery for NSCLC. Some people with mediastinal N2 lymph node involvement might benefit from post-operative radiotherapy.
For potentially curable SCLC cases, chest radiotherapy is often recommended in addition to chemotherapy. The ideal timing of these therapies (the optimal time to give radiotherapy and chemotherapy for improving survival) is not known.
If cancer growth blocks a short section of bronchus, brachytherapy (localized radiotherapy) may be given directly inside the airway to open the passage. Compared to external beam radiotherapy, brachytherapy allows a reduction in treatment time and reduced radiation exposure to healthcare staff. Evidence for brachytherapy, however, is less than that for external beam radiotherapy.
Prophylactic cranial irradiation (PCI) is a type of radiotherapy to the brain, used to reduce the risk of metastasis. PCI is most useful in SCLC. In limited-stage disease, PCI increases three-year survival from 15% to 20%; in extensive disease, one-year survival increases from 13% to 27%. For people who have NSCLC and a single brain metastasis, it is not clear if surgery is more effective than radiosurgery.
Recent improvements in targeting and imaging have led to the development of stereotactic radiation in the treatment of early-stage lung cancer. In this form of radiotherapy, high doses are delivered over a number of sessions using stereotactic targeting techniques. Its use is primarily in patients who are not surgical candidates due to medical comorbidities.
For both NSCLC and SCLC patients, smaller doses of radiation to the chest may be used for symptom control (palliative radiotherapy). The use of higher doses of radiotherapy for palliative care are not shown to prolong survival.
The chemotherapy regimen depends on the tumor type. SCLC, even relatively early stage disease, is treated primarily with chemotherapy and radiation. In SCLC, cisplatin and etoposide are most commonly used. Combinations with carboplatin, gemcitabine, paclitaxel, vinorelbine, topotecan, and irinotecan are also used. In advanced NSCLC, chemotherapy improves survival and is used as first-line treatment, provided the person is well enough for the treatment. Typically, two drugs are used, of which one is often platinum-based (either cisplatin or carboplatin). Other commonly used drugs are gemcitabine, paclitaxel, docetaxel,pemetrexed, etoposide or vinorelbine. Platinum-based drugs and combinations that include platinum therapy do not appear to be more beneficial for prolonging survival compared to other non-platinum medications, and may lead to a higher risk of serious adverse effects such as nausea, vomiting, anaemia, and thrombocytopenia, especially in people over the age of 70 years. There is not enough evidence to determine which chemotherapy approach is associated with the highest quality of life. There is also insufficient evidence to determine if treating people with NSCLC a second time when the first round of chemotherapy was not successful (second-line chemotherapy) causes more benefit or harm.
Adjuvant chemotherapy refers to the use of chemotherapy after apparently curative surgery to improve the outcome. In NSCLC, samples are taken of nearby lymph nodes during surgery to assist staging. If stage II or III disease is confirmed, adjuvant chemotherapy (including or not including postoperative radiotherapy) improves survival by 4% at five years. The combination of vinorelbine and cisplatin is more effective than older regimens. Adjuvant chemotherapy for people with stage IB cancer is controversial, as clinical trials have not clearly demonstrated a survival benefit.Chemotherapy before surgery in NSCLC that can be removed surgically may improve outcomes.
Chemotherapy may be combined with palliative care in the treatment of the NSCLC. In advanced cases, appropriate chemotherapy improves average survival over supportive care alone, as well as improving quality of life. With adequate physical fitness maintaining chemotherapy during lung cancer palliation offers 1.5 to 3 months of prolongation of survival, symptomatic relief, and an improvement in quality of life, with better results seen with modern agents. The NSCLC Meta-Analyses Collaborative Group recommends if the recipient wants and can tolerate treatment, then chemotherapy should be considered in advanced NSCLC.
Immunotherapy may be used for both SCLC and NSCLC. Vaccine-based immunotherapy treatment after surgery or radiotherapy may not lead to improved survival for people with Stage I-III NSCLC.
Several treatments can be provided via bronchoscopy for the management of airway obstruction or bleeding. If an airway becomes obstructed by cancer growth, options include rigid bronchoscopy, balloon bronchoplasty, stenting, and microdebridement. Laser photosection involves the delivery of laser light inside the airway via a bronchoscope to remove the obstructing tumor.
Palliative care when added to usual cancer care benefits people even when they are still receiving chemotherapy. These approaches allow additional discussion of treatment options and provide opportunities to arrive at well-considered decisions. Palliative care may avoid unhelpful but expensive care not only at the end of life, but also throughout the course of the illness. For individuals who have more advanced disease, hospice care may also be appropriate.
There is weak evidence to suggest that supportive care interventions (non-invasive interventions) that focus on well-being for people with lung cancer may improve quality of life. Interventions such as nurse follow-ups, psychotherapy, psychosocial therapy, and educational programs may be beneficial, however, the evidence is not strong (further research is needed).Counseling may help people cope with emotional symptoms related to lung cancer.Reflexology may be effective in the short-term, however more research is needed. There is no evidence to suggest that nutritional interventions or exercise programs result in an improvement in the quality of life for a person with lung cancer.
Outcomes in lung cancer according to clinical stage
Five-year survival (%)
Non-small-cell lung carcinoma
Small-cell lung carcinoma
Of all people with lung cancer in the US, 16.8% survive for at least five years after diagnosis. In England and Wales, between 2010 and 2011, overall five-year survival for lung cancer was estimated at 9.5%. Outcomes are generally worse in the developing world. Stage is often advanced at the time of diagnosis. At presentation, 30-40% of cases of NSCLC are stage IV, and 60% of SCLC are stage IV. Survival for lung cancer falls as the stage at diagnosis becomes more advanced: the English data suggest that around 70% of patients survive at least a year when diagnosed at the earliest stage, but this falls to just 14% for those diagnosed with the most advanced disease (stage IV).
Prognostic factors in NSCLC include presence of pulmonary symptoms, large tumor size (>3 cm), non-squamous cell type (histology), degree of spread (stage) and metastases to multiple lymph nodes, and vascular invasion. For people with inoperable disease, outcomes are worse in those with poor performance status and weight loss of more than 10%. Prognostic factors in small cell lung cancer include performance status, biological sex, stage of disease, and involvement of the central nervous system or liver at the time of diagnosis.
For NSCLC, the best prognosis is achieved with complete surgical resection of stage IA disease, with up to 70% five-year survival. People with extensive-stage SCLC have an average five-year survival rate of less than 1%. The average survival time for limited-stage disease is 20 months, with a five-year survival rate of 20%.
Lung cancer, incidence, mortality and survival, England 1971-2011
Worldwide, lung cancer is the most-common cancer among men in terms of both incidence and mortality, and among women has the third-highest incidence, and is second after breast cancer in mortality. In 2012, there were 1.82 million new cases worldwide, and 1.56 million deaths due to lung cancer, representing 19.4% of all deaths from cancer. The highest rates are in North America, Europe, and East Asia, with over a third of new cases in China that year. Rates in Africa and South Asia are much lower.
The population segment that is most likely to develop lung cancer is people aged over 50 who have a history of smoking. Unlike the mortality rate in men - which began declining more than 20 years ago, women's lung cancer mortality rates have risen over the last decades, and are just recently beginning to stabilize. In the US, the lifetime risk of developing lung cancer is 8% in men and 6% in women.
For every 3-4 million cigarettes smoked, one lung cancer death can occur. The influence of "Big Tobacco" plays a significant role in smoking. Young nonsmokers who see tobacco advertisements are more likely to smoke. The role of passive smoking is increasingly being recognized as a risk factor for lung cancer, resulting in policy interventions to decrease the undesired exposure of nonsmokers to others' tobacco smoke.
From the 1960s, the rates of lung adenocarcinoma started to rise in relation to other kinds of lung cancer, partially due to the introduction of filter cigarettes. The use of filters removes larger particles from tobacco smoke, thus reducing deposition in larger airways. However, the smoker has to inhale more deeply to receive the same amount of nicotine, increasing particle deposition in small airways where adenocarcinoma tends to arise. Rates of lung adenocarcinoma continues to rise.
In the US, both black men and black women have a higher incidence. Lung cancer rates are currently lower in developing countries. With increased smoking in developing countries, the rates are expected to increase in the next few years, notably in both China and India.
Also in the US, military veterans have a 25-50% higher rate of lung cancer primarily due to higher rates of smoking. During World War II and the Korean War, asbestos also played a role, and Agent Orange may have caused some problems during the Vietnam War.
Lung cancer is the third most-common cancer in the UK (around 46,400 people were diagnosed with the disease in 2014), and it is the most common cause of cancer-related death (around 35,900 people died in 2014).
Lung cancer was uncommon before the advent of cigarette smoking; it was not even recognized as a distinct disease until 1761. Different aspects of lung cancer were described further in 1810. Malignant lung tumors made up only 1% of all cancers seen at autopsy in 1878, but had risen to 10-15% by the early 1900s. Case reports in the medical literature numbered only 374 worldwide in 1912, but a review of autopsies showed the incidence of lung cancer had increased from 0.3% in 1852 to 5.66% in 1952. In Germany in 1929, physician Fritz Lickint recognized the link between smoking and lung cancer, which led to an aggressive antismoking campaign. The British Doctors' Study, published in the 1950s, was the first solid epidemiological evidence of the link between lung cancer and smoking. As a result, in 1964 the Surgeon General of the United States recommended smokers should stop smoking.
The connection with radon gas was first recognized among miners in the Ore Mountains near Schneeberg, Saxony. Silver has been mined there since 1470, and these mines are rich in uranium, with its accompanying radium and radon gas. Miners developed a disproportionate amount of lung disease, eventually recognized as lung cancer in the 1870s. Despite this discovery, mining continued into the 1950s, due to the USSR's demand for uranium. Radon was confirmed as a cause of lung cancer in the 1960s.
The first successful pneumonectomy for lung cancer was performed in 1933. Palliative radiotherapy has been used since the 1940s. Radical radiotherapy, initially used in the 1950s, was an attempt to use larger radiation doses in patients with relatively early-stage lung cancer, but who were otherwise unfit for surgery. In 1997, CHART was seen as an improvement over conventional radical radiotherapy. With SCLC, initial attempts in the 1960s at surgical resection and radical radiotherapy were unsuccessful. In the 1970s, successful chemotherapy regimens were developed.
Current research directions for lung cancer treatment include immunotherapy, which encourages the body's immune system to attack the tumor cells, epigenetics, and new combinations of chemotherapy and radiotherapy, both on their own and together. Many of these new treatments work through immune checkpoint blockade, disrupting cancer's ability to evade the immune system.
Other immunotherapy treatments interfere with the binding of programmed cell death 1 (PD-1) protein with its ligandPD-1 ligand 1 (PD-L1), and have been approved as first- and subsequent-line treatments for various subsets of lung cancers. Signaling through PD-1 inactivates T cells. Some cancer cells appear to exploit this by expressing PD-L1 in order to switch off T cells that might recognise them as a threat. Monoclonal antibodies targeting both PD-1 and PD-L1, such as pembrolizumab, nivolumab,atezolizumab, and durvalumab are currently in clinical trials for treatment for lung cancer.
Epigenetics is the study of small, usually heritable, molecular modifications--or "tags"--that bind to DNA and modify gene expression levels. Targeting these tags with drugs can kill cancer cells. Early-stage research in NSCLC using drugs aimed at epigenetic modifications shows that blocking more than one of these tags can kill cancer cells with fewer side effects. Studies also show that giving patients these drugs before standard treatment can improve its effectiveness. Clinical trials are underway to evaluate how well these drugs kill lung cancer cells in humans. Several drugs that target epigenetic mechanisms are in development. Histone deacetylase inhibitors in development include valproic acid, vorinostat, belinostat, panobinostat, entinostat, and romidepsin. DNA methyltransferase inhibitors in development include decitabine, azacytidine, and hydralazine.
The TRACERx project is looking at how NSCLC develops and evolves, and how these tumors become resistant to treatment. The project will look at tumor samples from 850 NSCLC patients at various stages including diagnosis, after first treatment, post-treatment, and relapse. By studying samples at different points of tumor development, the researchers hope to identify the changes that drive tumor growth and resistance to treatment. The results of this project will help scientists and doctors gain a better understanding of NSCLC and potentially lead to the development of new treatments for the disease.
The PI3K pathway has been investigated as a target for lung cancer therapy. The most promising strategies for targeting this pathway seem to be selective inhibition of one or more members of the class I PI3Ks, and co-targeted inhibition of this pathway with others such as MEK.
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