Negative Emotions and Breast Cancer Risk for Women with Benign Breast Disease: A Prospective Multicenter Cohort Study in China.

[BACKGROUND] Negative emotions are common in women with benign breast disease (BBD) and may influence breast cancer risk, but the relationship between these emotions, cancer development, and mitigating factors remains unclear. This study aimed to assess the impact of negative emotions on breast cancer risk and identify associated contributing factors.

[METHODS] This prospective cohort enrolled 3,535 women with BBD from 12 Chinese hospitals. Negative emotions were assessed using the irritability, depression, and anxiety (IDA) scale, and breast pain was evaluated with the breast pain score scale. Associations between negative emotions and breast cancer risk were analyzed using Cox regression models. Factors associated with negative emotions were identified with logistic regression, and mediation analysis was used to explore the roles of life satisfaction, sleep duration, and physical exercise.

[RESULTS] Nearly half (47%) of participants had high negative emotions (IDA ≥19). During follow-up, 2% developed breast cancer. High negative emotion was associated with a 2.78-fold increased cancer risk (HR = 2.78; 95% confidence interval, 1.34-5.76; P = 0.006), driven by depression and introverted irritability. Negative emotions correlated with physical inactivity, short sleep, life dissatisfaction, and severe breast pain. Life satisfaction (45%), sleep (7%) and exercise (19%) partially mediated the breast pain-negative emotion relationship.

[CONCLUSIONS] Negative emotions significantly increase breast cancer risk in women with BBD. Addressing modifiable factors like exercise, sleep, and life satisfaction may reduce emotional distress and potentially lower cancer risk.

[IMPACT] Integrating psychologic assessment and lifestyle interventions into BBD management could improve emotional well-being and mitigate cancer risk.