A 66-year-old man with a 40-pack-per-year history of smoking is investigated for hemoptysis. CXR reveals a central 3-cm mass near the left bronchus. His serum biochemistry is abnormal for elevated calcium, but there is no boney metastasis on the bone scan. Biopsy of the mass is positive for a type of lung cancer associated with paraneoplastic hypercalcemia.For the above patient with lung cancer, select the most likely cell type based on clinical description.