Quality of life and associated psychosocial factors in patients with invasive breast cancer receiving long-term anti-HER2 targeted therapy: a cross-sectional study

Introduction Breast cancer (BC) remains among the most prevalent malignancies in women worldwide, with human epidermal growth factor receptor 2 (HER2)-positive subtypes accounting for approximately 15%-20% of cases. Although targeted therapy has substantially improved outcomes, its prolonged course and associated adverse events, including cardiotoxicity and bone marrow suppression, may considerably undermine patients' quality of life (QoL). We evaluated factors associated with QoL in HER2-positive BC patients receiving anti-HER2 targeted therapy. Methods A total of 206 female patients with pathologically confirmed HER2-positive invasive BC receiving anti-HER2 targeted therapy at the Affiliated Hospital of Qingdao University between July 2024 and June 2025 were consecutively enrolled. Data were collected with standardized instruments: the Acceptance of Illness Scale (AIS), Social Support Rating Scale (SSRS), Strategies Used by People to Promote Health (SUPPH), and Functional Assessment of Cancer Therapy-Breast (FACT-B). Univariate analysis, Pearson correlation, and multiple linear regression examined factors associated with QoL. Structural equation modeling (SEM) using AMOS 28.0 then examined theory-driven associations grounded in Social Cognitive Theory and the Transactional Model of Stress and Coping. Results Mean scores were 89.60 ± 27.27 for QoL, 26.87 ± 6.64 for illness acceptance, 39.84 ± 12.21 for social support, and 94.86 ± 23.26 for self-efficacy, all within moderate ranges. QoL correlated positively with all three psychosocial variables (P < 0.01), most strongly with illness acceptance (r = 0.625). In the multivariable regression, infusion modality, illness acceptance, social support, and self-efficacy were independently associated with QoL. The SEM showed excellent fit (χ 2 /df = 1.257, RMSEA = 0.035, CFI = 0.982), with positive direct paths from illness acceptance (β = 0.558), social support (β = 0.238), and self-efficacy (β = 0.229) to QoL. Social support showed indirect associations with QoL through illness acceptance and self-efficacy. Self-efficacy also showed an indirect association with QoL through illness acceptance within the specified model. Discussion These findings suggest that QoL in patients receiving long-term anti-HER2 targeted therapy was associated with a combination of clinical and psychosocial factors, with illness acceptance, social support, and self-efficacy appearing particularly relevant. These associations should be regarded as correlational rather than causal, and prospective or interventional studies are needed to confirm them. The model offers a theoretical framework for these relationships and may inform the integration of psychosocial considerations into pharmaceutical care.