Final answer:
The most common cause of SVC syndrome is a tumor. When a tumor grows near or presses on the SVC, it can cause compression and prevent blood flow.
Step-by-step explanation:
The most common cause of SVC syndrome (compression of the SVC) is a tumor.
The SVC, or superior vena cava, is a large vein that carries deoxygenated blood from the upper body back to the heart. When a tumor grows near or presses on the SVC, it can cause compression and prevent blood from flowing freely through the vein. This can lead to symptoms such as swelling of the face, neck, and arms, difficulty breathing, and coughing.
Other less common causes of SVC syndrome include blood clots in the veins, infections, and noncancerous (benign) conditions like fibrous tumors.