This study will test the use of a web-enabled app that is integrated directly with patients' electronic health records, with and without tailored feedback. The app-based intervention is designed to improve patient-provider communication outside of clinic visits, resulting in improved symptom management and adjuvant endocrine therapy adherence among diverse patients with hormone receptor-positive breast cancer. The researchers will evaluate the impact of the intervention on a comprehensive set of outcomes, including rigorous measures of long-term adherence, quality of life, and costs.