Small cell lung cancer (SCLC) accounts for approximately 15% of bronchogenic carcinomas.
At the time of diagnosis, approximately 30% of patients with SCLC will have tumors confined to the hemithorax of origin, the mediastinum, or the supraclavicular lymph nodes. These patients are designated as having limited-stage disease (LD). Patients with tumors that have spread beyond the supraclavicular areas are said to have extensive-stage disease (ED).
Malignant non-small cell epithelial tumors of the lung are classified by the World Health Organization (WHO)/International Association for the Study of Lung Cancer (IASLC). There are three main subtypes of non-small cell lung cancer (NSCLC), including the following:
Squamous cell carcinoma (25% of lung cancers).
Adenocarcinoma (40% of lung cancers).
Large cell carcinoma (10% of lung cancers).
There are numerous additional subtypes of decreasing frequency.
SCLC is more responsive to chemotherapy and radiation therapy than other cell types of lung cancer; however, a cure is difficult to achieve because SCLC has a greater tendency to be widely disseminated by the time of diagnosis.
Incidence and Mortality
The overall incidence and mortality rates of SCLC in the United States have decreased during the past few decades.
Estimated new cases and deaths from lung cancer (SCLC and non-small cell lung cancer [NSCLC] combined) in the United States in 2013:
New cases: 228,190.
Lung cancer may present with symptoms or be found incidentally on chest imaging. Symptoms and signs may result from the location of the primary local invasion or compression of adjacent thoracic structures, distant metastases, or paraneoplastic phenomena. The most common symptoms at presentation are worsening cough, shortness of breath, and dyspnea. Other presenting symptoms include the following:
Symptoms may result from local invasion or compression of adjacent thoracic structures, such as compression involving the esophagus causing dysphagia, compression involving the laryngeal nerves causing hoarseness, or compression involving the superior vena cava causing facial edema and distension of the superficial veins of the head and neck. Symptoms from distant metastases may also be present and include neurological defect or personality change from brain metastases or pain from bone metastases.
Infrequently, patients with SCLC may present with symptoms and signs of one of the following paraneoplastic syndromes:
Inappropriate antidiuretic hormone secretion.
Cushing syndrome from secretion of adrenocorticotropic hormone.
Physical examination may identify enlarged supraclavicular lymphadenopathy, pleural effusion or lobar collapse, unresolved pneumonia, or signs of associated disease such as chronic obstructive pulmonary disease.