The Mediating Role of Illness Perception Between Psychological Capital and Subjective Well-Being in Breast Cancer Patients: A Cross-Sectional Study

Subjective well-being is increasingly recognized as a key health outcome among breast cancer patients, yet the psychological mechanisms that enhance it remain insufficiently understood. This study aimed to describe the levels of psychological capital, illness perception, and subjective well-being in breast cancer patients, examine their correlations, and test the mediating role of illness perception in the association between psychological capital and subjective well-being. A cross-sectional study was conducted among 256 breast cancer patients recruited by convenience sampling from a provincial tertiary hospital in Hefei, China. Patients were assessed using a self-designed general information questionnaire, the Positive Psychological Capital Questionnaire, the Brief Illness Perception Questionnaire, and the General Well-being Schedule. Data were analyzed using SPSS and PROCESS macro. The mean scores of psychological capital, illness perception, and subjective well-being were 102.31 ± 26.32, 38.54 ± 6.56, and 66.34 ± 14.07, respectively. Pearson’s correlation analysis showed that psychological capital was negatively correlated with illness perception (r = −0.648, p < 0.01), but positively correlated with subjective well-being (r = 0.620, p < 0.01). Illness perception was negatively correlated with subjective well-being (r = −0.792, p < 0.01). Mediation analysis showed that illness perception partially mediated the association between psychological capital and subjective well-being (B = 0.243, 95% CI: 0.194–0.295), accounting for 62.48% of the total effect (B = 0.388, 95% CI: 0.330–0.446). This study underscores the mediating role of illness perception in the association between psychological capital and subjective well-being among breast cancer patients. Reducing negative illness perceptions and enhancing psychological capital may help improve patients’ subjective well-being.