<s>[INST] context: If the superior or inferior vena cava is obstructed, the venous blood causes distention of the veins running from the anterior chest wall to the thigh.The lateral thoracic vein anastomoses with the superficial epigastric vein, a tributary of the great saphenous vein of the leg. In these circumstances, a touous varicose vein may extend from the axilla to the lower abdomenThe most common cause of superior vena cava syndrome is cancer.Primary or metastatic cancer in the upper lobe of the right lung can compress the superior vena cava.Lymphoma or other tumors located in the mediastinum can also cause compression of the superior vena cava.Less often, the superior vena cava can become blocked with a blood clot from within.Invasive medical procedures (Blood clot (thrombus) formation that causes superior vena cava syndrome is a complication of pacemaker wires, dialysis, and other intravenous catheters that are threaded into the superior vena cava)Infection (syphilis and tuberculosis) is another cause of superior vena cava syndrome. Sarcoidosis (a disease that results in masses of inflamed tissue) may also cause this syndrome. [/INST] question: SVC syndrome is most commonly associated with: | options: A: Mediastinal fibrosis B: Lymphoma C: Lung cancer D: TB mediastinitis | answer: C </s>