<prompt> Superior vena cava syndrome is caused most commonly by -AdenocarcinomaSquamous cell carcinomaSmall cell carcinomaLarge cell carcinoma  <response>: Superior vena cava syndrome results from obstruction of the superior vena cava by central upper lobe tumors, usually the small cell tumors - Cecil, 5e, p 1207 Cecil is a standard text book of Medicine by Saunders publication Superior vena cava SVC syndrome most frequently occurs with small-cell carcinoma, with bulkly enlargement of involved mediastinal lymph nodes and compression of the SVC. - Schwartz 9e 