Lung cancer is the leading cause of cancer-related mortality in the United States, with an estimated 160,000 deaths annually. Although lung cancer deaths have been declining among men since the early 1990s, lung cancer mortality has only recently begun to decline in women, likely reflecting gender differences in cigarette smoking and tobacco cessation patterns over the last 50 years. Cigarette smoking is the strongest modifiable risk factor for the development of lung cancer, accounting for 85%–90% of cases (1). Furthermore, smokers have a 20-fold increased risk of death from lung cancer compared to non-smokers. Still, other risk factors exist, including asbestos exposure, ionizing radiation, and exposure to carcinogenic chemicals and minerals. Research is ongoing regarding dietary and genetic risk factors.
Lung cancer is traditionally divided into two major classes: small cell lung cancer and non-small cell lung cancer (NSCLC). NSCLC accounts for approximately 85% of lung cancer cases. NSCLC can be further classified based upon histopathologic designations that include adenocarcinoma, squamous cell carcinoma (SqCC), and large cell carcinoma. Historically, SqCC was the most frequent type of NSCLC; however, adenocarcinoma has become twice as common as SqCC in the last 40 years, perhaps reflecting changes in cigarette composition over this time period (Table 52-1). Recently, the classification of lung adenocarcinoma was revised to provide more uniform terminology and diagnostic criteria across multidisciplinary providers (2). Notably, this revised classification scheme eliminated the category of bronchioloalveolar cell carcinoma (BAC).
TABLE 52-1DISTRIBUTION OF LUNG CANCER BY HISTOLOGY ||Download (.pdf) TABLE 52-1 DISTRIBUTION OF LUNG CANCER BY HISTOLOGY
|Histology ||Estimated Prevalence |
|Non-small cell lung cancer (NSCLC) ||85% |
|Adenocarcinoma ||40% |
|Squamous cell carcinoma ||20% |
|Large cell ||3% |
|Other NSCLCa ||22% |
|Small cell lung cancer ||15% |
The majority of patients with NSCLC are symptomatic at diagnosis. The most common symptoms arising from the primary tumor are cough, dyspnea, blood-tinged sputum, and chest pain. Local extension of the tumor within the chest can cause pleural or pericardial effusions, chest pain, hoarseness, brachial plexopathy, Horner's syndrome, and superior vena cava syndrome. Metastatic disease may present with weight loss, neurologic symptoms, or bony pain. Paraneoplastic syndromes such as syndrome of inappropriate antidiuretic hormone secretion (SIADH), Cushing's syndrome (ectopic corticotropin secretion), and Lambert-Eaton myasthenic syndrome are more commonly associated with small cell lung cancer, but NSCLC may be associated with hypercalcemia of malignancy or hypertrophic pulmonary osteoarthropathy.
Given the global burden of lung cancer deaths, a number of different screening strategies have been explored in order to improve lung cancer detection and survival. In the ...