eMedicine Specialties > Emergency Medicine > Hematology & Oncology

Neoplasms, Lung

Author: Mityanand Ramnarine, MD, Resident Physician, Department of Emergency Medicine, Albert Einstein College of Medicine at Long Island Jewish Medical Center
Coauthor(s): Gino A Farina, MD, Program Director, Associate Professor of Clinical Emergency Medicine, Department of Emergency Medicine, Long Island Jewish Medical Center, Albert Einstein College of Medicine
Contributor Information and Disclosures

Updated: Oct 21, 2009

Introduction

Background

Lung cancer was a rare entity in the early 1900s, but, by the end of the century, the disease had become the leading cause of preventable death in the United States.¹ Lung cancer is the leading cause of cancer-related death in the United States. In 2006, the disease caused more than 158,000 deaths—more than colorectal, breast, and prostate cancers combined.² The type of lung cancer in the United States as well as in many other countries have also changed in the past few decades such that the frequency of adenocarcinoma has risen and that of squamous cell carcinoma has declined.

Pathophysiology

Both environmental exposure to particular agents and an individual's susceptibility to these agents are thought to contribute to one's risk of developing lung cancer. In the United States, active smoking is responsible for 90% of lung cancer cases. Occupational exposures to carcinogens account for approximately 9-15%. The most common occupational risk factor for lung cancer is exposure to asbestos. Studies have shown radon exposure to be associated with 10% of lung cancer cases, while outdoor air pollution accounts for perhaps 1-2%.³ In addition, preexisting nonmalignant lung diseases, such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, and tuberculosis have all been shown to be associated with increased lung cancer rates.

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.³

Lung cancer is divided into 2 main categories: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Upon diagnosis, 80% of all lung cancers are NSCLC, which is further divided into squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. Adenocarcinoma overwhelmingly accounts for 40% of all cases of lung cancer. Squamous cell carcinoma is found in the central parts of the lung, whereas adenocarcinoma tumors are peripheral in origin. Large cell carcinoma composes only 15% of all lung cancers and appears to be decreasing in incidence because of improved diagnostic techniques.⁴

Frequency

United States

In the United States, lung cancer is the second most common cancer in women, and it is second only to prostate cancer in men. In 2008, 215,000 lung cancer cases occurred and 161,000 deaths were expected.⁶ From 1991-2005, the incidence of lung cancer in men has decreased each year by 1.8%; however, the incidence has increased by 0.5% per year for women over that same period. Lung cancer death rates for US women are among the highest in the world. Although in the United States death rates among males are higher than among females, rates for US men are still lower than rates among men in several other countries.⁷

National trends indicate that death rates are declining in men and are leveling off in women; paralleling trends in smoking prevalence over the past 50 years. The prevalence of smoking is approximately 21.6% in the nation and has remained unchanged over the past 15 years.

International

Lung cancer is the most commonly diagnosed cancer worldwide, with more than 1.35 million new cases detected each year and 1.18 million deaths.⁸ Among all cancers, lung cancer now has the highest mortality rate in most countries, with industrialized regions such as North America and Europe having the highest rates. The incidence of lung cancer is growing. 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. With increased smoking in developing countries, the incidence is expected to increase in the next few years, notably in China and India.

Mortality/Morbidity

Data compiled by the American Cancer Society shows lung cancer is, by far, the most common fatal cancer in men (31%) and in women (26%).

Data collected from 1995-2001 shows the 5-year relative survival rate for lung cancer was 15.7%, reflecting a steady but slow improvement from 12.5% in 1975.⁷

Despite advances in lung cancer therapy, the average 5-year survival rate is only 15%. However, the 5-year relative survival rate varies markedly depending on the stage at diagnosis:⁷

• 49% for local disease
• 16% for regional disease
• 2% for distant stage disease

Race

While lung cancer incidence rates are similar among African American and white women, lung cancer occurrence is approximately 45% higher among African American men than among white men.⁷ This increased incidence has been attributed to differences in smoking habits; however, recent evidence suggests a slight difference in susceptibility. From 1995-2001, the 5-year relative survival rate was 13% lower in African Americans compared with white individuals.⁷ This racial gap persisted within each stage at diagnosis for both men and women.

Sex

Males have a higher incidence of lung cancer, which probably parallels differences in smoking prevalence. As a result of the cigarette smoking epidemic, lung cancer death rates showed a steady increase through 1990, then began to decline among men. The lung cancer death rate among US women, who began regular cigarette smoking later than men, has begun to plateau after increasing for many decades.

• 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 often insidious, and it may produce no symptoms until the disease is well advanced. Early recognition of symptoms may be beneficial to outcome. Cough is reported to be the most common presenting symptom of lung cancer. Other respiratory symptoms include dyspnea, chest pain, and hemoptysis. Hemoptysis has been described as the one symptom often prompting more rapid presentation.⁹ At initial diagnosis, 20% of patients have localized disease, 25% of patients have regional metastasis, and 55% of patients have distant spread of disease. In addition, the patient's history may clue the physician in on a specific paraneoplastic syndrome (10-20% of patients).

Symptoms depend on location of cancer:¹⁰

• Endobronchial
  • Cough (45-75%)
  • Hemoptysis (57%)
  • Bronchial obstruction
  • Post obstructive 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, 2-18%)
  • Chylothorax (thoracic duct)
  • Palpitations (pericardial)
  • Dysphagia (enlargement of the subcarinal lymph nodes can cause dysphagia by compressing the middle third of the esophagus)
• 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 (secondary to phrenic nerve paralysis)
• 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 (6-25%)
  • Spinal cord impingement

Physical

Subtle findings on physical examination may provide clues for early detection. About one third of patients present with symptoms as a result of distant metastases. The most common sites of distant metastasis from lung cancer are the bones; liver; adrenal glands and intra-abdominal lymph nodes; brain and spinal cord; and lymph nodes and skin. Lung cancer can metastasize to virtually any bone, although the axial skeleton and proximal long bones are most commonly involved.

• Systemic findings
  • Unexplained weight loss
  • Low-grade fever
• Upper airway obstruction
  • Stridor
  • Wheezing
• Lower airway obstruction
  • Asymmetric breath sounds
  • Pleural effusion
  • Pneumothorax
  • Infiltrate
  • Post obstructive processes
• Respiratory insufficiency
  • Dyspnea and increased work of breathing
  • Retractions
  • Orthopnea
  • Cyanosis
• Extrapulmonary findings
  • Adenopathy
  • Clubbing
• Mechanical obstruction syndromes
  • Superior vena cava syndrome (usually small cell lung cancer) - Direct invasion by the primary tumor into the mediastinum or lymphatic spread with enlarged right paratracheal metastatic lymph nodes causes the 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
• Paraneoplastic syndromes¹¹
  • Cushing syndrome
  • Lambert-Eaton myasthenic syndrome: Gradual onset of proximal lower extremity weakness; proximal upper extremity weakness is usually less noticeable. The syndrome may be worse in the morning and improve during the day. Although extraocular muscle involvement is uncommon, ptosis is often found.
  • Hypercalcemia
  • Syndrome of inappropriate antidiuretic hormone secretion
  • Enlargement of the extremities, and painful, swollen joints (hypertrophic osteoarthropathy)
• Ogilvie intestinal pseudo-obstruction
  • Nausea
  • Vomiting
  • Early satiety
  • Abdominal discomfort
  • Weight loss
  • Change in bowel habits

Causes

Clearly, because all lung cancers do not occur in smokers and the vast majority of smokers do not develop lung cancer, other etiological factors can independently or jointly in conjunction with smoking cause lung cancer. These factors include genetics, arsenic exposure, radiation exposure, and other environmental carcinogens.¹² Although genetic factors probably contribute in all populations, the contribution of other factors is population-specific. Some causes include the following:

• Smoking (in more than 90% of patients)
• Asbestos exposure
• Radon
• Halogen ether exposure
• Chronic interstitial pneumonitis
• Inorganic arsenic exposure
• Radioisotope exposure, ionizing radiation
• Atmospheric pollution
• Chromium, nickel exposure
• Vinyl chloride

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