Lung cancer
Lung cancer (primary lung cancer), or frequently if somewhat incorrectly known as bronchogenic carcinoma, is a broad term referring to the main histological subtypes of primary lung malignancies that are mainly linked with inhaled carcinogens, with cigarette smoke being a key culprit.
This article will broadly discuss all the histological subtypes as a group, focusing on their common aspects and for further details please refer to the specific articles on each subtype described below.
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Epidemiology
Lung cancer is a leading type of cancer, equal in prevalence to breast cancer 13. It is the leading cause of cancer mortality worldwide; accounting for ~20% of all cancer deaths 1.
Risk factors
The major risk factor is cigarette smoking which is implicated in 90% of cases and increase the risk of lung cancer, which can be divided by histological subtype 10:
- squamous cell lung cancer: 11x (men), 15x (women)
- small cell lung cancer: 10x (men), 25x (women)
- large cell lung cancer: 7x (men), 8x (women)
- lung adenocarcinoma: 4x (men and women)
Other risk factors:
- asbestos: 5x increased risk
- occupational exposure: uranium, radon, arsenic, chromium
- diffuse lung fibrosis: 10x increased risk
- chronic obstructive pulmonary disease
Associations
Various paraneoplastic syndromes can arise in the setting of lung cancer:
- endocrine/metabolic
- SIADH causing hyponatremia: small-cell subtype
- ACTH secretion (Cushing syndrome): carcinoid and small-cell subtypes
- carcinoid syndrome
- gynecomastia
- adrenal insufficiency (Addison disease): from bilateral metastases 7
- hyperparathyroidism: NSCLC can produce parathyroid hormone (extremely rare) 8
- hypocalcemia: occurs in the setting of skeletal metastases; especially associated with NSCLC 6
- PTH-related peptide (PTHrp) causing hypercalcemia: squamous cell carcinoma
- neurological
- polyneuropathy
- myelopathy
- limbic encephalitis: particularly associated with SCLC 9
- cerebellar degeneration
- Lambert-Eaton myasthenia syndrome
- other
- finger clubbing
- hypertrophic pulmonary osteoarthropathy (HPOA): squamous cell carcinoma subtype
- nephrotic syndrome
- polymyositis 3
- dermatomyositis 3
- eosinophilia
- acanthosis nigricans
- thrombophlebitis: adenocarcinoma subtype
Clinical presentation
Patients with lung cancer may be asymptomatic in up to 50% of cases. Cough and dyspnea are rather non-specific symptoms that are common amongst those with lung cancer.
Central tumors may result in hemoptysis and peripheral lesions with pleuritic chest pain.
Pneumonia, pleural effusion, wheeze, lymphadenopathy are not uncommon. Other symptoms may be secondary to metastases (bone, contralateral lung, brain, adrenal glands, and liver, in frequency order for NSCLC 12) or paraneoplastic syndromes.
Pathology
The term bronchogenic carcinoma is somewhat loosely used to refer to primary malignancies of the lung that are associated with inhaled carcinogens 1 and includes four main histological subtypes. These are broadly divided into non-small cell carcinoma and small cell carcinoma as they differ clinically regarding presentation, treatment, and prognosis:
-
non-small cell lung cancer (NSCLC) (80%)
-
adenocarcinoma (35%)
- most common cell type overall
- most common in women
- most common cell type in non-smokers but still most patients are smokers
- peripheral
-
squamous cell carcinoma (30%)
- strongly associated with smoking
- most common carcinoma to cavitate
- poor prognosis
-
large-cell carcinoma (15%)
- peripherally located
- very large, usually >4 cm
-
adenocarcinoma (35%)
-
small cell carcinoma (20%)
- almost always in smokers
- metastasizes early
- most common primary lung malignancy to cause paraneoplastic syndromes and SVC obstruction
- worst prognosis
Other malignant pulmonary neoplasms include lymphoma and sarcoma (rare).
Each subtype has a different radiographic appearance, demographic, and prognosis:
- squamous-cell carcinoma of the lung
- adenocarcinoma of the lung
- large cell carcinoma of the lung
- small cell carcinoma of the lung
Antibodies and markers
Several antibodies or markers from tissue samples may be useful in the diagnosis and prognostication of disease. These include
- programmed death-ligand 1 (PD-L1)-targeted monoclonal antibodies
- thyroid transcription factor 1 (TTF-1): expressed in most lung cancer except squamous cell cancer
Staging
Treatment and prognosis
Treatment and prognosis vary not only with stage but also with cell type. In general, surgery, chemotherapy, and radiotherapy are offered according to the stage, resectability, operability, and functional status.
Non-small cell carcinoma
-
treatment
- operable disease (stage I to IIIA): surgery
- unresectable disease: neoadjuvant chemotherapy, radiotherapy
- advanced disease: palliative combined chemotherapy
-
prognosis (5-year survival rates):
- local (stage I): 55-67%
- locally advanced (stages II-IIIA): 23-40%
- advanced (stages IIIB and IV): 1-3%
Small-cell carcinoma
-
treatment
- limited disease: chemoradiotherapy
- extensive disease: palliative combined chemotherapy
-
prognosis: poor
- limited: 5-year survival rate 15-25%
- extensive: 2-year survival 20% (with palliative combined chemotherapy and supportive care)
See also
Related Radiopaedia articles
Chest
- imaging techniques
-
chest x-ray
-
approach
- adult
- pediatric
- neonatal
-
airspace opacification
- differential diagnoses of airspace opacification
- lobar consolidation
-
atelectasis
- mechanism-based
- morphology-based
- lobar lung collapse
- chest x-ray in the exam setting
- cardiomediastinal contour
- chest radiograph zones
- tracheal air column
- fissures
- normal chest x-ray appearance of the diaphragm
- nipple shadow
-
lines and stripes
- anterior junction line
- posterior junction line
- right paratracheal stripe
- left paratracheal stripe
- posterior tracheal stripe/tracheo-esophageal stripe
- posterior wall of bronchus intermedius
- right paraspinal line
- left paraspinal line
- aortic-pulmonary stripe
- aortopulmonary window
- azygo-esophageal recess
- spaces
- signs
- air bronchogram
- big rib sign
- Chang sign
- Chen sign
- coin lesion
- continuous diaphragm sign
- dense hilum sign
- double contour sign
- egg-on-a-string sign
- extrapleural sign
- finger in glove sign
- flat waist sign
- Fleischner sign
- ginkgo leaf sign
- Golden S sign
- Hampton hump
- haystack sign
- hilum convergence sign
- hilum overlay sign
- Hoffman-Rigler sign
- holly leaf sign
- incomplete border sign
- juxtaphrenic peak sign
- Kirklin sign
- medial stripe sign
- melting ice cube sign
- more black sign
- Naclerio V sign
- Palla sign
- pericardial fat tag sign
- Shmoo sign
- silhouette sign
- snowman sign
- spinnaker sign
- steeple sign
- straight left heart border sign
- third mogul sign
- tram-track sign
- walking man sign
- water bottle sign
- wave sign
- Westermark sign
-
approach
- HRCT
-
chest x-ray
- airways
- bronchitis
- small airways disease
-
bronchiectasis
- broncho-arterial ratio
- related conditions
- differentials by distribution
- narrowing
-
tracheal stenosis
- diffuse tracheal narrowing (differential)
-
bronchial stenosis
- diffuse airway narrowing (differential)
-
tracheal stenosis
- diverticula
- pulmonary edema
-
interstitial lung disease (ILD)
- drug-induced interstitial lung disease
-
hypersensitivity pneumonitis
- acute hypersensitivity pneumonitis
- subacute hypersensitivity pneumonitis
- chronic hypersensitivity pneumonitis
- etiology
- bird fancier's lung: pigeon fancier's lung
- farmer's lung
- cheese workers' lung
- bagassosis
- mushroom worker’s lung
- malt worker’s lung
- maple bark disease
- hot tub lung
- wine maker’s lung
- woodsman’s disease
- thatched roof lung
- tobacco grower’s lung
- potato riddler’s lung
- summer-type pneumonitis
- dry rot lung
- machine operator’s lung
- humidifier lung
- shower curtain disease
- furrier’s lung
- miller’s lung
- lycoperdonosis
- saxophone lung
-
idiopathic interstitial pneumonia (mnemonic)
- acute interstitial pneumonia (AIP)
- cryptogenic organizing pneumonia (COP)
- desquamative interstitial pneumonia (DIP)
- non-specific interstitial pneumonia (NSIP)
- idiopathic pleuroparenchymal fibroelastosis
- lymphoid interstitial pneumonia (LIP)
- respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)
- usual interstitial pneumonia / idiopathic pulmonary fibrosis (UIP/IPF)
-
pneumoconioses
- fibrotic
- non-fibrotic
-
lung cancer
-
non-small-cell lung cancer
-
adenocarcinoma
- pre-invasive tumors
- minimally invasive tumors
- invasive tumors
- variants of invasive carcinoma
- described imaging features
- adenosquamous carcinoma
- large cell carcinoma
- primary sarcomatoid carcinoma of the lung
- squamous cell carcinoma
- salivary gland-type tumors
-
adenocarcinoma
- pulmonary neuroendocrine tumors
- preinvasive lesions
-
lung cancer invasion patterns
- tumor spread through air spaces (STAS)
- presence of non-lepidic patterns such as acinar, papillary, solid, or micropapillary
- myofibroblastic stroma associated with invasive tumor cells
- pleural invasion
- vascular invasion
- tumors by location
- benign neoplasms
- pulmonary metastases
- lung cancer screening
- lung cancer staging
-
non-small-cell lung cancer