Introduction: While 5-10 years of adjuvant endocrine therapy (AET) substantially reduces recurrence risk and improves survival in breast cancer patients, adherence remains suboptimal. Research has documented various factors influencing adherence, including psychological distress and AET-related side effects. However, breast cancer patients may adopt different decision-making patterns when confronted with factors, which may influence adherence outcomes. A clearer understanding of these patterns during AET is needed to inform targeted adherence interventions to improve AET adherence.

Methods: From February 2025 to February 2026, semi-structured online interviews were conducted with 21 breast cancer patients recruited through purposive sampling. Interview data were analyzed using thematic analysis to identify participants’ decision-making characteristics, from which distinct decision-making patterns were derived. Data interpretation was guided by Janis and Mann’s conflict decision-making model.

Results: Four distinct decision-making patterns corresponding to the model were identified: 1) Vigilance pattern. Patients with this pattern proactively used multiple information sources before decision-making, demonstrated careful deliberation and active participation during the process, maintained stable post-decision attitudes. This pattern showed high medication adherence; 2) Hypervigilance pattern. This pattern was marked by information overload, leading to high decisional pressure and excessive deliberation. These factors prompted stress-driven responses to treatment challenges, post-decision regret, and ultimately resulted in unstable medication adherence; 3) Unconflicted change pattern. Patients with this pattern demonstrated limited information-seeking, relied on intuitive decision-making, and participated passively. Consequently, they engaged in minimal post-decision reflection, and their medication adherence was readily influenced by external circumstances; 4) Defensive avoidance pattern: This pattern was characterized by deliberate avoidance of negative information, limited engagement in decision-making, and reliance on others while resisting personal responsibility for decisions, ultimately resulting in physician-led medication adherence.

Conclusion: Decision-making patterns during AET are associated with medication adherence and exhibit distinct characteristics. Tailoring interventions to these patterns may improve AET adherence and health outcomes.