Brief Summary: This study investigates the bone-related side effects caused by immunotherapy drugs such as nivolumab and pembrolizumab in patients with melanoma. Nivolumab and pembrolizumab are immunotherapy drugs (drugs that boost your immune system) used to prevent cancer from coming back in patients with melanoma. Specifically, researchers want to learn if there is any relationship between receiving immunotherapy and bone density (thickness) measured by a dual-energy X-ray absorptiometry (DXA) scan or bone turnover markers (which indicate levels of bone loss) found in the blood. This study may provide researchers with more information on bone loss and may help prevent bone loss in future patients.

Detailed Description: PRIMARY OBJECTIVES: I. Characterize the effects of adjuvant immune checkpoint inhibitor (ICI) therapy (nivolumab or pembrolizumab) on measures of bone health, including bone density and bone turnover markers, in a prospectively recruited cohort of 40 adult patients (\>= 40 years) with melanoma diagnoses seen at MD Anderson Cancer Center. II. Identify associations of baseline demographic, clinical, and general bone loss risk factors (e.g., age, corticosteroid use) and tumor characteristics with bone loss in the same cohort. OUTLINE: Patients undergo collection of blood samples after starting immunotherapy and then at 6 and 12 months. Patients also undergo DXA scan over 5-10 minutes after starting immunotherapy and at 12 months.