Adjuvant endocrine therapy for premenopausal women with breast cancer: Patient adherence and physician prescribing practices in Mexico

Background: In resource-constrained settings, data regarding breast cancer patients' adherence to endocrine therapy (ET) and physicians' prescribing practices is limited. This study aims to decrease this knowledge gap in a real-world clinical practice. Methods: Premenopausal women with stage 0-III hormone-sensitive breast cancer and receiving adjuvant ET during the past 1-5 years were identified in three Mexican referral centers. Participants' self reported ET compliance, clinicopathologic characteristics, ET-related knowledge and beliefs, experienced adverse effects, social support, and patient-physician relationships were evaluated. Physician ET prescribing practices were compared with the gold standard according to international and national guidelines to assess clinicians' adherence to standard-of-care prescription. Results: In total, 95/132 (72%) and 35/132 (27%) participants reported complete and acceptable adherence, respectively. Incomplete adherence was mainly attributed to forgetfulness, adverse effects, and unwillingness to take ET. Being employed/studying (p = 0.042), worrying about long-term ET use (p = 0.031), and experiencing >7 ET-related symptoms (p = 0.018) were associated with incomplete adherence. Guideline-endorsed regimens were prescribed in 84/132 (64%) patients, while the rest should have undergone ovarian function suppression (OFS) but instead received tamoxifen monotherapy. Conclusions: Premenopausal Mexican women self-report remarkably high rates of adequate ET adherence. However, a considerable proportion misses >1 doses/month, usually because of forgetfulness. Notably, only 64% receive standard-of-care ET due to suboptimal prescription of OFS. Interventions that remind patients to take their ET, refine physicians' knowledge on the importance of OFS in high-risk patients, and increase access to OFS could prove pivotal to enhance optimal ET implementation and adherence, which could translate into improved patient outcomes. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).