Cancer Health Center

Overview

Superior vena cava syndrome (SVCS) is an array of symptoms caused by the impairment of blood flow through the superior vena cava (SVC) to the right atrium. Symptoms that prompt suspicion of this syndrome include dyspnea, coughing, and swelling of the face, neck, upper trunk, and extremities. In rare instances, patients may complain of hoarseness, chest pain, dysphagia, and hemoptysis. Physical signs that may be noted on presentation are neck vein distention, thoracic vein distention, edema of the face or upper extremities, plethora, and tachypnea. Rarely, cyanosis, Horner syndrome, and a paralyzed vocal cord may also be present.[1]

SVCS is usually a sign of locally advanced bronchogenic carcinoma. Survival depends on the status of the patient's disease. When small cell bronchogenic carcinoma is treated with chemotherapy, the median survival times with or without SVCS are almost identical (42 weeks or 40 weeks, respectively). The 24-month survival rate is 9% in patients without SVCS and 3% in those with the syndrome. When the malignancy is treated with radiation therapy, 46% of patients who have non-small cell lung cancer experience relief of symptoms compared with 62% of patients who have small cell bronchogenic carcinoma. The 2-year survival rate of 5% is almost the same for both groups.[2]

Most non-Hodgkin lymphoma patients with SVCS respond to appropriate chemotherapy or to combined modality regimens.

Etiology/Physiology

Since SVCS was first described by William Hunter in 1757, the spectrum of underlying conditions associated with it has shifted from tuberculosis and syphilitic aneurysms of the ascending aorta to malignant disorders. Almost 95% of SVCS cases described in published modern series are due to cancer; the most common cause is small cell bronchogenic carcinoma, followed by squamous cell carcinoma of the lung, adenocarcinoma of the lung, non-Hodgkin lymphoma, and large cell carcinoma of the lung.[3] A nonmalignant cause of SVCS in cancer patients is thrombosis that is associated with intracaval catheters or pacemaker wires.[4] A rare cause of SVCS is fibrosing mediastinitis, either idiopathic or associated with histoplasmosis.[5] Additional rare causes of SVCS include metastatic germ cell neoplasms, metastatic breast cancer, colon cancer, Kaposi sarcoma, esophageal carcinoma, fibrous mesothelioma, Behçet syndrome, thymoma, substernal thyroid goiter, Hodgkin lymphoma, and sarcoidosis.[6]

Knowledge of the anatomy of the SVC and its relationship to the surrounding lymph nodes is essential to understanding the development of the syndrome. The SVC is formed by the junction of the left and right brachiocephalic veins in the mid third of the mediastinum. The SVC extends caudally for 6 to 8 cm, coursing anterior to the right mainstem bronchus and terminating in the superior right atrium, and extends anteriorly to the right mainstem bronchus. The SVC is joined posteriorly by the azygos vein as it loops over the right mainstem bronchus and lies posterior to and to the right of the ascending aorta. The mediastinal parietal pleura is lateral to the SVC, creating a confined space, and the SVC is adjacent to the right paratracheal, azygous, right hilar, and subcarinal lymph node groups. The vessel itself is thin-walled, and the blood flowing therein is under low pressure. Thus, when the nodes or ascending aorta enlarge, the SVC is compressed, blood flow slows, and complete occlusion may occur.