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Neoplasms, Lung
Updated: Sep 20, 2007
Introduction
Background
Bronchogenic carcinoma is the most common fatal cancer in the United States, accounting for 28% of all cancer deaths. It is one of the few cancers with a continually rising mortality rate. Smoking is the most important etiologic factor linked to lung cancer and is responsible for as many as 85% of cases.
Pathophysiology
The current multiple hit theory suggests that a series of toxic cellular insults disrupts orderly genetic reproduction. Symptoms ultimately develop from the uncontrolled disorganized growth that interferes with local or distant anatomy or physiologic processes.
The histologic subtypes include adenocarcinoma (40%), squamous cell (17%), small oat cell (25%), large cell (15%), and other (3%) carcinomas.
Frequency
United States
Approximately 175,000 new cases of lung cancer are diagnosed each year. Lung cancer is the most common cancer in women, and it is second only to prostate cancer in men. The prevalence is approximately 70 cases per 100,000 population.
International
The incidence of lung cancer is growing. Among all cancers, lung cancer now has the highest mortality rate in most countries, with industrialized nations having the highest rates. The incidence of lung cancer parallels the incidence of cigarette smoking, with a latency of 20 years. The highest incidence occurs in the United Kingdom and Poland, where it is more than 100 cases per 100,000 population per year. The lowest incidence rate occurs in Senegal and Nigeria, where it is less than 1 case per 100,000 population per year.
Mortality/Morbidity
- Of all cancers, lung cancer is estimated to be responsible for the greatest number of years of life lost to any cancer.
- The incidence and mortality data mirror one another. Survival rates have not changed despite aggressive intervention.
Race
- Compared with white males, African American males have a 50% increased incidence of lung cancer (116 per 100,000 versus 79 per 100,000). This increased incidence has been attributed to differences in smoking habits; however, recent evidence suggests a slight difference in susceptibility.
Sex
Males have a higher incidence of lung cancer, which probably parallels differences in smoking prevalence. According to the Centers of Disease Control and Prevention (CDC), approximately 50% of men are current or former smokers compared with 41% of women. It is estimated that, in 2001, 90,100 men and 67,300 women will die of lung cancer.
- During the last 10 years, the incidence of lung cancer has increased more rapidly in women than in men.
- Women have a higher incidence of localized disease at presentation and of adenocarcinoma.
- Women typically are younger when they present with symptoms.
Age
Lung cancer occurs predominately in persons aged 50-70 years.
Clinical
History
Lung cancer is common, often insidious, and it may produce no symptoms until the disease is well advanced. Early recognition of symptoms may be beneficial to outcome. At initial diagnosis, 20% of patients have localized disease, 25% of patients have regional metastasis, and 55% of patients have distant spread of disease. The patient's history may suggest specific paraneoplastic syndromes (10-20% of patients).
Types of lung cancer involvement may include the following:
- Endobronchial
- Cough (45-75%)
- Hemoptysis (57%)
- Bronchial obstruction
- Postobstructive complications (eg, pneumonitis, pneumonia, effusion)
- Mediastinal
- Dyspnea
- Postprandial coughing (esophageal)
- Wheezing
- Stridor (upper airway obstruction, 2-18%)
- Hoarseness (left vocal cord paralysis due to recurrent laryngeal nerve impingement)
- Chylothorax (thoracic duct)
- Palpitations (pericardial)
- Pleural
- Chest pain (27-49%)
- Dyspnea (37-58%)
- Cough (45-75%)
- Neurologic
- Arm weakness and paresthesias (brachial plexus impingement)
- Miosis ptosis and anhidrosis (cervical sympathetic chain, Horner syndrome)
- Dyspnea (phrenic nerve)
- Metastatic (8-68%)
- Weight loss
- Cachexia
- Central nervous system
- Headache
- Altered mental status
- Seizure
- Meningismus
- Ataxia
- Nausea and/or vomiting
- Vascular
- Phlebitis
- Thromboembolism (Trousseau syndrome)
- Musculoskeletal
- Bone pain
- Spinal cord impingement
Physical
Physical examination findings are often unremarkable; however, subtle findings may provide clues for early detection.
- Systemic findings
- Unexplained weight loss
- Low-grade fever
- Upper airway obstruction
- Stridor
- Wheezing
- Lower airway obstruction
- Asymmetric breath sounds
- Pleural effusion
- Pneumothorax
- Infiltrate
- Postobstructive processes
- Respiratory insufficiency
- Dyspnea and increased work of breathing
- Retractions
- Orthopnea
- Cyanosis
- Extrapulmonary findings
- Adenopathy
- Clubbing
- Mechanical obstruction syndromes
- Superior vena cava syndrome
- Feeling of fullness in the head
- Dyspnea
- Cough
- Dilated neck veins
- Prominent venous pattern on the face and the chest
- Upper extremity and facial edema
- Papilledema
- Facial cyanosis
- Plethora
- Pancoast tumor
- Superior sulcus tumor that causes pain (eg, in the shoulder, medial forearm, arm, scapula)
- Horner syndrome
- Bone destruction
- Hand muscle atrophy
- Acute spinal cord compression
- Paraplegia
- Sensory deficits
- Urinary incontinence or retention
- Vertebral pain
- Superior vena cava syndrome
- Paraneoplastic syndromes
- Cushing syndrome
- Lambert-Eaton syndrome
- Myasthenic syndrome
- Hypercalcemia
- Syndrome of inappropriate antidiuretic hormone secretion
- Ogilvie intestinal pseudo-obstruction
- Nausea
- Vomiting
- Early satiety
- Abdominal discomfort
- Weight loss
- Change in bowel habits
Causes
- Smoking (in more than 90% of patients)
- Asbestos exposure
- Halogen ether exposure
- Chronic interstitial pneumonitis
- Inorganic arsenic exposure
- Radioisotope exposure
- Atmospheric pollution
- Other metal exposure
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References
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Further Reading
Keywords
lung neoplasm, bronchogenic carcinoma, lung cancer, lung malignancy, adenocarcinoma, squamous cell carcinoma, SCC, oat cell carcinoma, large cell carcinoma, smoking, tobacco, passive smoke, secondhand smoke
