A 50-year-old male presents with chest tightness and shortness of breath for 2 months, and left chest pain for over 20 days (worsening at night). Physical examination shows mild swelling of the face, neck, and chest wall, dilated chest wall veins, a thumb-sized axillary lymph node (no tenderness, mobile), heart rate 108 bpm (regular rhythm), and absent breath sounds in the left lung. The most likely diagnosis is: