Hospital readmissions are common after major cancer surgery, leading to poorer patient outcomes, increased mortality and additional costs. In this study, Clinical and Engineering Approaches to Readmission (CLEAR) Care Companion Application, investigators aim to utilize a smartphone application that tracks concerning postoperative symptoms and provides educational interventions to determine if this can minimize delays in communication between patients and medical providers, increase patient satisfaction with the care received, and reduce or lessen the severity of readmissions.