A 67-year-old man is referred for evaluation after he was found to have a 4-cm central left lung mass that is not amenable to a wedge resection. He reports being able to walk only 40 feet without becoming short of breath. He is unable to walk up one flight of stairs without stopping. Three months ago, he was able to walk 2 to 3 miles daily. On physical examination, he is afebrile; pulse is 62 beats/min, respirations are 12 breaths/min, and blood pressure is 142/86 mm Hg. Jugular venous distention and bilateral lower extremity edema are noted. Computed tomography of the chest with intravenous contrast and positron emission tomography are unremarkable other than the 4-cm left lung mass.

Required:
What is the best next step in management?