<prompt> Which is the most common metastatic disease causing SVC syndrome?Ca BronchusCa BreastCa VeebraeCa Stomach  <response>: Breast cancer is the most common metastatic disease causing SVC syndrome. Lung cancer is the most common cause of SVC syndrome. Non Hodgkins lymphoma is the second most common cause. Primary mediastinal malignancies such as thymoma and germ cell tumors account for less than 2 cases. 