Probiotic Yogurt Supplement in Reducing Diarrhea in Patients With Metastatic Kidney Cancer Being Treated With Vascular Endothelial Growth Factor-Tyrosine Kinase Inhibitor

Inclusion Criteria:

* Cytologically or pathologically verified diagnosis of renal cell carcinoma (RCC)
* Diagnosis of RCC that is defined as metastatic by standard criteria (American Joint Committee on Cancer \[AJCC\] 7th edition, 2010)
* Planned treatment with any VEGF-TKI, treatment has not yet begun
* Ability to understand and the willingness to sign a written informed consent
* Ability to read and write English
* Documented consent to participation to include the following study specific procedures:

  * Be able to provide up to six serial stool collections at home and deliver to FedEx location that day as per standard operating procedure
  * Have three 10-ml blood samples taken during a routine clinic visit
  * To not take probiotic supplements except as oriented
  * If randomized to the probiotic-supplemented group (the yogurt-based supplement Activia), be willing to comply with daily intake and record this intake as a component of a dietary log; the patient will be asked not to take any yogurt or yogurt-containing foods beyond this
  * If randomized to the probiotic-restricted group, agree not to consume yogurt or yogurt-containing foods
  * Maintain a dietary log and stool frequency log

Exclusion Criteria:

* Patients with a known intolerance to lactose or other constituents of Activia
* Patients with irritable bowel syndrome, Crohn's disease, or other clinically significant gastrointestinal (GI) related condition that might confound the VEGF-TKI-related-diarrhea endpoint
* Patients taking antibiotics or who plan to begin taking antibiotics
* Any other condition that would, in the investigator's judgment, contraindicate the patient's participation in the clinical study due to safety concerns or compliance with clinical study procedures (including compliance issues related to feasibility/logistics)