A 72-year-old woman is evaluated in follow-up for a recent diagnosis of multiple myeloma. She presented with an 8-month history of progressive fatigue and dyspnea with exertion, but has had no other symptoms. Medical history is unremarkable, and she takes no medications.
On physical examination, temperature is 37.6 °C (99.7 °F), blood pressure is 142/86 mm Hg, pulse rate is 90/min, and respiration rate is 14/min. No focal neurologic deficits are observed. Cardiopulmonary examination is normal, and the remainder of the physical examination is unremarkable.
Initial laboratory studies showed a hemoglobin level of 9.2 g/dL (92 g/L), serum calcium level of 10.2 mg/dL (2.6 mmol/L), and serum creatinine level of 1.3 mg/dL (115 µmol/L).
A monoclonal IgG κ band of 4.2 g/dL was seen on serum protein electrophoresis and immunofixation, and myeloma was confirmed with a bone marrow aspirate and biopsy showing clonal plasma cells representing 70% of the overall cellularity.
A skeletal survey demonstrates diffuse osteopenia and a T12 compression fracture with 50% height loss. No lytic lesions are seen.
In addition to starting chemotherapy, which of the following is the most appropriate treatment?