Lung Cancer

Lung cancer
Classification and external resources

Three-dimensional volume rendering of a thorax CT showing a tumor in the lung (marked by arrow)

10 34
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 characterized by uncontrolled [7]

The most common [9]

Survival depends on stage, overall health, and other factors. Overall, 15% of people in the United States diagnosed with lung cancer [11]


Age-adjusted incidence of lung cancer by histological type[4]
Histological type Incidence (per 100,000 per year)
All types 66.9
Adenocarcinoma 22.1
Squamous-cell carcinoma 14.4
Small-cell carcinoma 9.8

Lung cancers are classified according to [12]

Non-small-cell lung carcinoma

The three main subtypes of NSCLC are adenocarcinoma, squamous-cell lung carcinoma, and large-cell lung carcinoma.[2]

Nearly 40% of lung cancers are adenocarcinoma, which usually originates in peripheral lung tissue.[14]

Squamous-cell carcinoma accounts for about 30% of lung cancers. They typically occur close to large airways. A hollow cavity and associated necrosis are commonly found at the center of the tumor.[8]

About 9% 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.[8]

Small-cell lung carcinoma


Small-cell lung carcinoma (microscopic view of a core needle biopsy)

In [2]


Four main histological subtypes are recognized, although some cancers may contain a combination of different subtypes.[2]


The lung is a common place for metastasis of tumors from other parts of the body. Secondary cancers are classified by the site of origin; e.g., breast cancer that has spread to the lung is called metastatic breast cancer. Metastases often have a characteristic round appearance on chest radiograph.[16]

Typical immunostaining in lung cancer[2]
Histological type Immunostain
Squamous-cell carcinoma CK5/6 positive

CK7 negative

Adenocarcinoma CK7 positive

TTF-1 positive

Large-cell carcinoma TTF-1 negative
Small-cell carcinoma TTF-1 positive

CD56 positive

Chromogranin positive

Synaptophysin positive

Primary lung cancers themselves most commonly metastasize to the brain, bones, liver, and [17]

Signs and symptoms

Symptoms and signs that may suggest lung cancer include:[2]

If the cancer grows in the airway, it may obstruct airflow, causing breathing difficulties. The obstruction can lead to accumulation of secretions behind the blockage, and predispose to pneumonia.[2]

Depending on the type of tumor, so-called [2]

Many of the symptoms of lung cancer (poor appetite, weight loss, fever, fatigue) are not specific.[10]


Cancer develops following genetic damage to DNA. This genetic damage affects the normal functions of the cell, including cell proliferation, programmed cell death (apoptosis) and DNA repair. As more damage accumulates, the risk of cancer increases.[20]



NIH graph showing how a general increase in sales of tobacco products in the USA in the first four decades of the 20th century (cigarettes per person per year) led to a corresponding rapid increase in the incidence of lung cancer during the 1930s, ’40s and ’50s (lung cancer deaths per 100,000 male population per year)


Cross section of a human lung: The white area in the upper lobe is cancer; the black areas are discoloration due to smoking.



Radon gas




Air pollution

Outdoor air pollution has a small effect on increasing the risk of lung cancer.[4]


Some people have a genetic predisposition to lung cancer. In relatives of people with lung cancer, the risk is increased 2.4 times. This may be due to genetic polymorphisms.[38]

Other causes

Numerous other substances, occupations, and environmental exposures have been linked to the genesis of cancer in lung tissue of humans. In its List of Classifications by Cancer Sites,[39]the International Agency for Research on Lung Cancer (IARC) states there is “sufficient evidence” to show the following are carcinogenic in lung:

  • Aluminum production
  • Arsenic and inorganic arsenic compounds
  • Beryllium and beryllium compounds
  • Bis-(chloromethyl) ether
  • Methyl ether (technical grade)
  • Cadmium and cadmium compounds
  • Chromium(VI) compounds
  • Coal (indoor emissions from household coal burning)
  • Combustion (incomplete)
  • Coal gasification
  • Coal-tar pitch
  • Coke production
  • Diesel engine exhaust
  • Gamma radiation
  • Hematite mining (underground)
  • Iron and steel founding
  • MOPP (vincristine-prednisone-nitrogen mustard-procarbazine mixture)
  • Nickel compounds
  • Painting
  • Plutonium
  • Radon-222 and its decay products
  • Rubber production industry
  • Silica dust (crystalline)
  • Soot
  • Sulfur mustard
  • X-radiation


Similar to many other cancers, lung cancer is initiated by activation of [42]



Chest radiograph showing a cancerous tumor in the left lung

Performing a [10]


CT scan showing a cancerous tumor in the left lung

Lung cancer often appears as a [2]


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 the prognosis and potential treatment of lung cancer.[2]

The initial evaluation of non-small-cell lung cancer (NSCLC) staging uses the [47]

For both NSCLC and SCLC, the two general types of staging evaluations are clinical staging and surgical staging. Clinical staging is performed prior to 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 intra- or postoperatively, and is based on the combined results of surgical and clinical findings, including surgical sampling of thoracic lymph nodes.[8]


Prevention is the most cost-effective means of mitigating lung cancer development. 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.[48]

Policy interventions to decrease [51]

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.[52]

The long-term use of supplemental vitamin A,[56]




Treatment for lung cancer depends on the cancer’s specific cell type, how far it has [2]



squamous-cell carcinoma, seen as a white area near the bronchi

If investigations confirm NSCLC, the [62]


In most cases of early-stage NSCLC, removal of a lobe of lung ([63]


In SCLC, chemotherapy and/or radiotherapy is typically used.[68]



For potentially curable SCLC cases, chest radiotherapy is often recommended in addition to chemotherapy.[8]

If cancer growth blocks a short section of bronchus, [74]

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%.[75]

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 in a small number of sessions using stereotactic targeting techniques. Its use is primarily in patients who are not surgical candidates due to medical comorbidities.[76]

For both NSCLC and SCLC patients, smaller doses of radiation to the chest may be used for symptom control (palliative radiotherapy).[77]


The chemotherapy regimen depends on the tumor type.[8]

Small-cell lung carcinoma

Even if relatively early stage, SCLC is treated primarily with chemotherapy and radiation.[81]

Non-small cell lung carcinoma

In advanced NSCLC, chemotherapy improves survival and is used as first-line treatment, provided the patient is well enough for the treatment.[83]

Advanced NSCLC is often treated with [85]

Adjuvant chemotherapy


Adjuvant chemotherapy for patients with stage IB cancer is controversial, as clinical trials have not clearly demonstrated a survival benefit.[90]

Palliative care

In patients with terminal disease, palliative care or hospice management may be appropriate.[92]

Chemotherapy may be combined with palliative care in the treatment of the NSCLC. In advanced cases, appropriate chemotherapy improves [96]


Prognosis in lung cancer according to clinical stage[47]
Clinical stage Five-year survival (%)
Non-small cell lung carcinoma Small cell lung carcinoma
IA 50 38
IB 47 21
IIA 36 38
IIB 26 18
IIIA 19 13
IIIB 7 9
IV 2 1

Prognostic factors in NSCLC include presence or absence of pulmonary symptoms, [98]

Prognosis is generally poor. Of all patients with lung cancer, 15% survive for five years after diagnosis.[8]

For NSCLC, the best prognosis is achieved with complete surgical resection of stage IA disease, with up to 70% five-year survival.[1]

According to data provided by the [102]




  no data
  ≤ 5
  ≥ 55


Lung cancer distribution in the United States

Worldwide, lung cancer is the most common cancer in terms of both [2]

For every 3–4 million cigarettes smoked, one lung cancer death occurs.[107]

The role of [4]


From the 1960s, the incidence of lung adenocarcinoma started to rise relative to other types of lung cancer. This is partly 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.[114]


Lung cancer was uncommon before the advent of cigarette smoking; it was not even recognized as a distinct disease until 1761.[122]

The connection with [125]

The first successful [129]

With small-cell lung carcinoma, initial attempts in the 1960s at surgical resection[132]


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External links


This article uses material from the Wikipedia article Lung Cancer, which is released under the Creative Commons Attribution-Share-Alike License 3.0.

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