This study is being done to learn more about energy needs and muscle function during treatment for bladder cancer. These insights can help improve future patient care. The study team found in a previous study that resting energy can be different than what estimates show. Patients with bladder cancer are known to suffer a decline in physical resilience over time. Monitoring patients to understand these changes better could help design future treatments with these vulnerabilities in mind.

The investigators' long-term goal is to improve cachexia treatment for patients with cancer. The project is significant because identifying cachexia earlier in its onset allows for earlier and more successful treatment. Major barriers to early detection and treatment are: 1) clear specific lab tests to confirm the diagnosis and 2) identifying when resting energy expenditure (REE) increases. It is the investigators' expectation that at the completion of these descriptive studies, key factors will be identified to guide earlier detection and treatment of cachexia. Platinum-based chemotherapy and surgery are a dual-phase treatment regimen to treat bladder cancer that has a high risk of worsening cachexia compared to other cancer types not requiring such an intensive treatment regimen. Inhibition of Growth differentiation factor 15 (GDF-15) is a promising preventive strategy against cachexia in patients with bladder cancer. Understanding GDF-15 and REE changes over the course of treatment could inform proactive rather than reactive strategies to support the health of these patients and translate to patients with other types of cancer. The objective of this application is to assess changes in GDF-15 and REE levels during the treatment course for advanced bladder cancer.

Inclusion Criteria:

• Confirmed cancer diagnosis
• Scheduled for platinum-based chemotherapy followed by radical cystectomy
• Adequate renal and cardiac function for platinum-based chemotherapy

Exclusion Criteria:

• Prior chemotherapy or radiotherapy for bladder cancer
• Severe cardiac, renal, hepatic, respiratory or metabolic diseases
• Pregnant or breastfeeding
• Uncontrolled conditions that could affect study outcomes

Potential patients will be scheduled for treatment (chemotherapy and radical cystectomy) for bladder cancer at the University of Kansas Health System.