Pilot Study of Bone Mineral Density Changes During Anti-PD-1 Immunotherapy

Inclusion Criteria: 1. Age ≥ 18 years. 2. Patients planning to start or within the first four weeks of treatment with anti-PD-1 immune checkpoint inhibitor therapy either alone or in combination with chemotherapy for curative intent for a known cancer diagnosis (use of immunotherapy must be FDA-approved and not experimental). 3. Life expectancy of at least 12 months per the discretion of the treating physician. Exclusion Criteria: 1. Patients ineligible for anti-PD-1 therapy. 2. Patients with metastatic disease. 3. Patients planning treatment with dual immune checkpoint inhibitor therapy. 4. Bony fractures in the pelvis, bilateral hips/femurs, thoracic spine, or lumbar spine. 5. Known osteoporosis or osteopenia. 6. Planned or previous treatment with denosumab, zoledronic acid, or other bisphosphonate therapy in the last six months. 7. Parathyroid gland disorders, rheumatoid arthritis (unless well-controlled off active biologic therapy without chronic steroid use), CKD stage IV/V, or ESRD. 8. Inability to comply with study procedures. 9. Inability to lie flat for 20-25 minutes during an imaging session. 10. Pregnant or breastfeeding patients. 11. Medical or psychiatric co-morbidities that, in the opinion of the treating physician, would prevent the patient from successfully participating in the study.