A 50-year-old man complains of swelling of the neck and shoness of breath for 7 days. He has noticed some nasal stuffiness with hoarseness of his voice for about 4 weeks and had attributed these symptoms to an upper respiratory infection. He denies the use of alcohol but has smoked two packs of cigarettes per day for 35 years. Lately, he feels as though something is pushing against his throat. On physical examination, the patient's face appears ruddy and swollen. The jugular veins are distended. Following sign is observed in the patient. Chest x ray was done with the following findings. What is the most likely diagnosis?