Radiation therapy (RT) is a key component in the treatment of breast and prostate cancer. However, patients may experience significant side effects. Patients can accurately self-report side effects from RT and these patient-reported outcomes (PROs) can direct communication between patient and healthcare provider (HCP), and facilitate joint decision making. Patients state that using mobile phone applications (apps) to collect PROs (mPROs) is easily incorporated into their daily routines, allowing them to engage at a time and pace that suits them. When mPRO collection is combined with remote symptom monitoring by HCPs, these systems result in improvements in symptom control and quality of life. Currently, patients receiving RT are seen by a Radiation Oncologist once per week during RT and once every few months after RT has finished. Recent evaluations indicate that patients and physicians consider the number of visits to be too frequent during RT, and too infrequent immediately after RT. This research will use weekly mPROs (remotely monitored by RT HCP) to determine if a patient needs (or wants) to be seen by a RT HCP during and/or immediately after RT. Using mPROs to optimize RT patient assessment processes will ensure patients are seen if and when required. For a patient, this could result in reduced time and costs at the hospital. For the physician, resources could be re-allocated to improve access to RT services. Using mPROs after RT has the potential for earlier treatment of side effects, which has been linked to improved survival and quality of life.