Text Messaging in Patients on Adjuvant Endocrine Therapy for Breast Cancer

1. The primary objective is to compare rates of persistence (continuation) of any endocrine therapy (ET) between patients assigned to standard of care follow-up (control arm) versus standard of care plus a bi-directional text messaging intervention (intervention arm) 2. The secondary objectives are: (i) To assess time to permanent discontinuation of ET (switching from an aromatase inhibitor to another ET is permitted). The investigators will also account for treatment breaks. (ii) To assess QOL at baseline, and at 6 and 12 months after initiation of ET (FACT-ES1, Brief Pain Inventory2, Overall Treatment Burden3,4, individual symptom LASA scales4) and compare between arms (iii) To assess adherence self-efficacy (SEAMS5 tool, Voils Extent of Non-Adherence Scale6), financial burden (COST tool7,8), beliefs about medications (modified BMQ tool9,10), and perceived ability to communicate with one's physician (PEPPI11 tool) and compare between arms (iv) To compare the time to endocrine therapy discontinuation in both the intervention and control arms (v) To characterize factors (including clinicopathologic features, socioeconomic status, and comorbidities) associated with non-adherence in both the intervention arm and the control arm, which may enable us to identify women who are at particularly high risk of non-adherence. (vi) To assess adherence to medication as reported through the BETA-Text intervention (vii) To collect the time to onset and trend of severity of side effects in women assigned to the text messaging intervention.