General Information About Small Cell Lung Cancer (SCLC)
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).
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 2015:
- New cases: 221,200.
- Deaths: 158,040.
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:
- Chest pain.
- Weight loss.
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.
- Paraneoplastic cerebellar degeneration.
- Lambert-Eaton myasthenic syndrome.
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.
Treatment options for patients are determined by histology, stage, and general health and comorbidities of the patient. Investigations of patients with suspected SCLC focus on confirming the diagnosis and determining the extent of the disease.
The procedures used to determine the presence of cancer include the following:
- Physical examination.
- Routine laboratory evaluations.
- Chest x-ray.
- Chest computed tomography scan with infusion of contrast material.
Before a patient begins lung cancer treatment, an experienced lung cancer pathologist must review the pathologic material. This is critical because SCLC, which responds well to chemotherapy and is generally not treated surgically, can be confused on microscopic examination with NSCLC. Immunohistochemistry and electron microscopy are invaluable techniques for diagnosis and subclassification, but most lung tumors can be classified by light microscopic criteria.
Prognosis and Survival
Regardless of stage, the current prognosis for patients with SCLC is unsatisfactory despite improvements in diagnosis and therapy made during the past 25 years. Without treatment, SCLC has the most aggressive clinical course of any type of pulmonary tumor, with median survival from diagnosis of only 2 to 4 months. About 10% of the total population of SCLC patients remains free of disease during the 2 years from the start of therapy, which is the time period during which most relapses occur. Even these patients, however, are at risk of dying from lung cancer (both small and non-small cell types). The overall survival at 5 years is 5% to 10%.[1,5-7]
An important prognostic factor for SCLC is the extent of disease. Patients with LD have a better prognosis than patients with ED. For patients with LD, median survival of 16 to 24 months and 5-year survivals of 14% with current forms of treatment have been reported.[1,6,8,9] Patients diagnosed with LD who smoke should be encouraged to stop smoking before undergoing combined-modality therapy because continued smoking may compromise survival.
Improved long-term survival in patients with LD has been shown with combined-modality therapy.[9,11][Level of evidence: 1iiA] Although long-term survivors have been reported among patients who received either surgery or chemotherapy alone, chemotherapy combined with thoracic radiation therapy (TRT) is considered the standard of care. Adding TRT increases absolute survival by approximately 5% over chemotherapy alone.[11,13] The optimal timing of TRT relative to chemotherapy has been evaluated in multiple trials and meta-analyses with the weight of evidence suggesting a small benefit to early TRT.[1,14,15][Level of evidence: 1iiA]
In patients with ED, median survival of 6 to 12 months is reported with currently available therapy, but long-term disease-free survival is rare.
Thoracic radiation may also improve long-term outcomes for these patients.
All patients with this type of cancer may appropriately be considered for inclusion in clinical trials at the time of diagnosis. Information about ongoing clinical trials is available from the NCI Web site.
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