While sunitinib can be very helpful to treat kidney cancer, these medications can also cause side effects, including heart damage. Studies performed in the past did not look at heart function in detail, so the investigators do not know what happens to the heart when people start sunitinib treatment. The aim of the study is to prospectively study acute effects of sunitinib on heart function, overall fitness and blood markers of heart disease.

Participants will undergo cardiac MRI, maximal exercise testing(VO2 peak), blood and urine samples before and after 2 treatments of sunitinib. An extra blood sample will be collected the 2nd week of the first treatment to check blood levels of sunitinib. We will also examine routine CT scans to study body composition.

Inclusion Criteria:

• Histologic diagnosis of metastatic renal cell carcinoma
• Eligible to receive first-line sunitinib
• Willingness to attend Cross Cancer Institute and University of Alberta for study-related assessments
• Karnofsky Performance Status (KPS)82 ≥ 70
• Age ≥ 18 years of age
• Adequate creatinine clearance to receive gadolinium
• All patients with bone metastases are eligible; those with lesions identified at weight-bearing bones will undergo plain films to evaluate fracture risk prior to CPET;
• Fluent in English language
• No contraindication to MRI or other concern eg., metallic implants, claustrophobia

Exclusion Criteria:

• Prior systemic therapy for mRCC
• Documented history of major cardiac event in last year i.e. MI, unstable angina, CABG, symptomatic CHF, CVA or TIA, or pulmonary embolism
• Pregnancy
• Other severe condition or abnormality that, in the judgement of the investigator or treating oncologist, would make participation in this study inappropriate
• Unstable brain metastases

Patients with renal cell carcinoma scheduled to receive sunitinub.