Synchronizing Treatment with Circadian Rhythm: A descriptive and exploratory analysis of adherence to endocrine therapy in breast cancer [abstract]

Abstract

Background: Breast cancer is the most commonly diagnosed cancer among adult women and represents a disruptive event in the life cycle, with recognized impacts on quality of life. The most recurrent tumors in this context are hormone-dependent (Li et al., 2022), and adjuvant endocrine therapy is considered an essential component of the therapeutic plan. It is widely used to reduce the risk of breast cancer recurrence and mortality, especially when administered over long periods (Uslu et al., 2023). Despite its proven effectiveness, deficits in prospective memory (i.e., the ability to plan an intention, retain it over time, and retrieve it when appropriate) may underlie unintentional nonadherence. Although the literature suggests the presence of subjective complaints of prospective memory in this context (Rodrigues et al., 2023), few studies have focused on understanding which factors influence these impairments in oncological settings. International studies have suggested that prospective memory may fluctuate throughout the day, influenced by circadian rhythm (i.e., morningness-eveningness/chronotype). Therefore, aligning medication intake with the optimal time of cognitive performance may reduce lapses in treatment adherence. Objectives: This preliminary study presents initial data from a project aimed at (i) characterizing behavioral patterns of adherence to endocrine therapy in breast cancer survivors and (ii) exploring the relationship between chronotype and prospective memory complaints. Methods: The sample included 65 women (Mage=47.5; SD=9.3; range=28–65), all undergoing endocrine therapy. Self-report instruments used were the Horne and Ostberg Morningness-Eveningness Questionnaire and the Metacognitive Prospective Memory Inventory—Short Form. Descriptive and correlational analyses were performed. Results: Of the participants, 69.2% had an intermediate chronotype, 18.5% morning-type, and 12.3% evening-type. Most were taking tamoxifen and/or exemestane, with 43.8% medicating at night. A significant association was found between chronotype and medication timing (X²(4) = 10.5; p = .032). There was also a trend for evening and intermediate types to report fewer prospective memory complaints, though not statistically significant. Conclusions: Preliminary results indicate that chronotype may affect medication timing preferences in breast cancer survivors on endocrine therapy. Aligning adherence with circadian rhythms could support personalized treatment strategies. Further research is needed to clarify its link with prospective memory complaints.