Superior Vena Cava Syndrome with Malignant Causes

A 58-year-old man presents with a 2-week history of progressive dyspnea on exertion, neck swelling, decreased appetite, and fatigue. There is no history of syncope or dysphagia. He smoked cigarettes until 5 years ago. The physical examination reveals a heart rate of 105 beats per minute, a respiratory rate of 20 breaths per minute, and superficial vascular distention over the neck, chest, and upper abdomen. Stridor is not present. How should his case be evaluated and managed?