In 2009, over 215,000 cases of lung cancer were anticipated which represented 15% of all cancer diagnoses. Lung cancer is the second leading cancer diagnosis in men and women behind prostate cancer and breast cancer, respectively, with a slightly higher prevalence of lung cancer diagnosis in men as compared to women. However, the incidence of lung cancer in men is declining while the incidence in women is increasing. In 2009, over 161,000 deaths attributed to lung cancer were anticipated which makes lung cancer the leading cause of death secondary to cancer in both sexes.1
There are four major subtypes of lung cancer: small cell, squamous cell, adenocarcinoma, and large cell. Squamous cell, adenocarcinoma, and large cell are collectively referred to as non–small-cell lung cancer (NSCLC). NSCLC represents approximately 85% of the lung cancer diagnoses while small-cell lung cancer (SCLC) represents only approximately 15% of lung cancer diagnoses. Adenocarcinoma represents the most common histology of NSCLC and is associated with a high incidence of distant metastasis at diagnosis. Squamous cell is the second most common histology of NSCLC followed by large cell, the least common histology in NSCLC. An important subtype of adenocarcinoma is bronchoalveolar, which is more responsive to erlotinib. Finally, SCLC is a very aggressive histology but occurs in only 15% of patients with lung cancer. Adenocarcinoma and large-cell lung cancer generally present as peripheral lesions in the lung whereas squamous cell and small cell histologies commonly present as central lesions, often causing hemoptysis or postobstructive pneumonia.2,3
Smoking, either voluntary or second-hand cigarette smoke, causes the overwhelming majority of cases of lung cancer. The risk of lung cancer increases with the amount and the duration of smoking. One's smoking history is defined by the packs per day (amount) and duration of smoking (eg, 2 packs per day × 20 years = 40 pack years). The risk of lung cancer decreases after smoke cessation but it remains above the risk of a nonsmoker for the rest of a former smoker's life.4 Asbestos exposure increases one's risk of lung cancer by fivefold, and it is synergistic with smoking for causing lung cancer. Although the most common lung cancer associated with asbestos exposure is NSCLC; patients with mesothelioma almost always have a history of asbestos exposure. Other risk factors associated with lung cancer include radon exposure, ionizing radiation, a diet low in fruit/vegetables/β-carotene/vitamin E, a family history of lung cancer, and certain occupational exposures (ie, coal, arsenic, nickel, and other mining jobs).
The most common signs and symptoms of lung cancer include cough, increased sputum production, pleuritic chest pain, dyspnea, wheezing, and stridor; however, these symptoms are also common in smokers in general. One's suspicion of lung cancer should increase if the patient experiences hemoptysis. Extrapulmonary symptoms associated with lung cancer include bone pain and/or fracture from bone metastasis, neurologic deficits secondary to brain metastasis, and spinal cord compression secondary to bone metastasis in ...