Brief Summary: The purpose of this study is to understand the metabolism of cancers involving the kidney, including renal cell carcinomas and urothelial cell carcinomas, and how kidney cancers use different types of fuel to support tumor growth. This study uses specially labeled nutrient tracers of compounds normally found circulating in the blood. The nutrients (glucose, fructose, glutamine, acetate, and lactate) are also found in common foods. A nutrient tracer will be given to the participants through an intravenous (IV) catheter during surgery or biopsy, and blood will be collected every 30 minutes during the infusion to monitor safety parameters and the nutrient tracers. The investigators will collect a tissue sample after the completion of surgery. Participants not having an infusion will have their tissue collected after surgery or biopsy. Participation in this study will not change patient care. All patients will receive standard of care treatment as determined by their doctors.

Detailed Description: The purpose of this study is to understand the metabolism of kidney cancers (renal cell carcinomas and urothelial cell carcinomas involving the kidney) in patients. Metabolism is the term used to describe how cells take up different nutrients and convert them to energy and materials needed for cell growth. In cancer, metabolism is hijacked to support the needs of cancer cells. Cancer cells can use multiple nutrients in the blood to fuel their growth, but it is not known what materials cancer cells make with those nutrients in patients. Many participants in this study will be infused with a 13C-labeled nutrient during their surgery or biopsy. 13C means that the carbon in the nutrient is heavier than 12C carbons that are the most abundant carbon atoms in nature. 13C carbons account for about 1% of natural carbon atoms are not radioactive or harmful in any way. Using the tissue collected during or after surgery and/or biopsy, the researchers can track how the heavier 13C carbons from the infused nutrient are being used to make different materials that cancer cells need to grow. The researchers hope to understand how kidney cancers change their metabolism to adapt, grow, and survive in patients. The knowledge learned from this study will be used to support the development of therapies that target metabolic adaptations, and the development of new non-invasive imaging techniques that will improve the care and survival of future kidney cancer patients.