Mucoadhesive Oral Wound Rinse in Preventing and Treating Stomatitis in Patients With ER- or PR-Positive Metastatic or Locally Recurrent Breast Cancer That Cannot be Removed by Surgery Receiving Everolimus

PRIMARY OBJECTIVES: I. Evaluate whether use of prophylactic MuGard (mucoadhesive oral wound rinse) in participants being treated with everolimus will reduce the rate of stomatitis. SECONDARY OBJECTIVES: I. Compare symptoms from mouth sores in patients receiving MuGard compared with those receiving best supportive care. II. Evaluate the rate of everolimus dose adjustment or therapy discontinuation as a result of stomatitis in participants treated with MuGard prophylaxis versus best supportive care. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive mucoadhesive oral wound rinse orally (PO) as a gentle swish for 30-60 seconds 3-6 times daily beginning on day 1 of everolimus therapy and continuing for up to 6 months in the absence of unacceptable toxicity. ARM II: Patients receive no intervention. After completion of study treatment, patients are followed up within 7 days.