Background: Advances in medical technology have significantly increased cancer survival rates, shifting the focus of cancer care from clinical survival toward long-term quality of life management. While a cancer diagnosis is widely known to affect health-related quality of life (HRQoL), its direct impact is often difficult to distinguish because it is deeply intertwined with aging and socioeconomic factors. Understanding the specific nature of these challenges is essential for developing effective survivorship support systems in the post-treatment phase.

Objectives: This study investigates the association between cancer diagnosis and the EQ-5D index, specifically focusing on identifying which dimensions of daily life are most vulnerable to cancer-related impairment. Furthermore, it examines HRQoL variations according to the time elapsed since diagnosis to inform targeted survivorship care.

Methods: We conducted a population-based analysis using data from 5,431 adults who participated in the 2024 Korea National Health and Nutrition Examination Survey (KNHANES). The independent variable was the history of cancer diagnosis, while the dependent variables were the EQ-5D index and its five sub-dimensions (Mobility, Self-care, Usual activities, Pain/Discomfort, Anxiety/Depression). Multiple linear regression was used to assess the overall EQ-5D index, and multivariate logistic regression was employed to analyze the five specific dimensions. Subgroup analysis among survivors evaluated the impact of time since diagnosis (0–2, 3–9, and 10+ years). All models were adjusted for demographic, socioeconomic, and mental health factors (PHQ-9).

Results: In the crude analysis, cancer diagnosis appeared to significantly lower the overall EQ-5D index (F=15.17, p<0.001). However, in the comprehensive adjusted model, cancer diagnosis was not significantly associated with the overall EQ-5D index (p=0.9005), whereas aging and mental health status showed stronger associations. In contrast, dimension-specific analysis revealed a localized impact: cancer survivors faced a significantly higher risk of impairment in Self-care (OR=1.682, 95% CI: 1.105–2.561) and Usual activities (OR=1.354, 95% CI: 1.013–1.809). No significant differences were found in the domains of Mobility, Pain/Discomfort, or Anxiety/Depression. Among survivors, HRQoL did not differ significantly by time elapsed since diagnosis (p=0.0949), while age and education remained significant predictors.

Conclusion & Implications: This study highlights that a history of cancer does not necessarily manifest as a decline in the overall HRQoL index (EQ-5D index), but rather as a specific functional vulnerability in domains such as 'self-care' and 'usual activities.' Although factors like aging and mental health play significant roles, the finding that a cancer diagnosis remains a distinct risk factor for functional impairment is critical. Therefore, cancer survivorship management must shift from a purely medical follow-up model toward a 'comprehensive functional support framework' that integrates physical rehabilitation with mental health interventions. Regardless of the time elapsed since diagnosis, priority should be given to restoring the patient's daily autonomy and practical operational capabilities.