REVIEW Interventions to improve endocrine therapy adherence in breast cancer survivors: what is the evidence? Ekim Ekinci 1 & Salima Nathoo 2 & Thushara Korattyil 2 & Aisha Vadhariya 3 & Hanna A. Zaghloul 1 & Polly A. Niravath 4 & Susan M. Abughosh 3 & Meghana V. Trivedi 2 Received: 13 July 2017 /Accepted: 29 December 2017 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Purpose Endocrine therapy reduces the risk of breast cancer recurrences and mortality in hormone receptor-positive (HR+) breast cancer survivors. However, non-adherence to treatment remains a significant problem. The aim of this study was to review current literature and ongoing trials to identify interventions employed to improve adherence to adjuvant endocrine therapy (AET) in breast cancer survivors. Methods We searched PubMed and the National Library of Medicine registry of clinical trials using the terms Bbreast cancer^ and Badherence^ or Bcompliance^ and Bintervention^ and Bmedication^ or Bendocrine therapy^ or Bhormone therapy^ to identify published studies as well as ongoing clinical trials. Results Three hundred and sixty-three studies were identified; five studies met the inclusion criteria. Most studies enrolled postmenopausal women diagnosed with early stage HR+ breast cancer. Providing educational materials was the most common intervention implemented to improve adherence to one or more aromatase inhibitors. None of the studies found a significant improvement in adherence with the intervention evaluated. Twelve clinical trials investigating various interventions, mostly based on technology, to improve AET adherence were also identified. Conclusions Improving adherence to AET in HR+ breast cancer survivors is an urgent medical need. While newer clinical trials are overcoming some of the limitations seen with published studies, tailored interventions led by clinicians need further investigation. Implications for cancer survivors Our study highlights the unmet clinical need to develop and test feasible interventions to improve AET adherence in HR+ breast cancer survivors to extend their long-term survival. Keywords Breast cancer . Endocrine therapy . Medication adherence . Compliance . Intervention Introduction Breast cancer is the most common type of cancer and the second most prevalent cause of cancer death among women in the USA [1]. In 2017, 255,180 new cases of invasive breast cancer and 41,070 breast cancer deaths are estimated to occur [1]. About 70 to 80% of breast cancer is positive for estrogen receptors and/or progesterone receptors, collectively called hormone receptors (HR) [2]. For HR-positive (HR+) breast cancer, the standard systemic therapies include selective estro- gen receptor modulators (SERMs) such as tamoxifen or aro- matase inhibitors (AIs) (anastrozole, letrozole, and exemestane) to inhibit estrogen synthesis. While HR+ breast cancer is less aggressive and has better 5-year survival, adju- vant endocrine therapy (AET) further reduces the risk of re- currence, distant metastasis, and mortality in early stage breast * Meghana V. Trivedi mtrivedi@uh.edu 1 Department of Pharmacy, Houston Methodist Hospital, 6565 Fannin Street, DB1-09, Houston, TX 77030, USA 2 Department of Pharmacy Practice and Translational Research, University of Houston College of Pharmacy, 4849 Calhoun Rd, Houston, TX 77204, USA 3 Department of Pharmaceutical Outcomes and Policy, University of Houston College of Pharmacy, 4849 Calhoun Rd, Houston, TX 77204, USA 4 Department of Internal Medicine, Hematology/Oncology Division, Houston Methodist Hospital, 6550 Fannin Street, Houston, TX 77030, USA Journal of Cancer Survivorship https://doi.org/10.1007/s11764-017-0674-4