Abstract
Background: Depression has a high incidence among patients with breast cancer, but the relationship between depression and cancer-related physiological changes is not clear.Objectives: To explore the effect of T lymphocytes on breast cancer depression and the patient’s quality of life.Methods: This is a cross-sectional study. A total of 93 breast cancer patients with depression were recruited, 46 of whom underwent T lymphocyte, cortisol, BDNF, TNF-α, and IL-1β collection. We analysed the correlation between the indicators in these 46 participants and constructed two intermediary structural equations between their T lymphocytes and depression, as well as their T lymphocytes and their quality of life.Results: The results showed that CD4+ had a positive correlation with BDNF (r=0.334, P=0.023) and that BDNF had a negative correlation with HAMD-24 (r=-0.390, P=0.007). Both CD3+ and CD8+ cells were negatively correlated with cortisol (r=-0.358, P=0.015, r=-0.411, P=0.005), and cortisol was positively correlated with FACT-B (r=0.435, P=0.003). The equations including CD4+, BDNF, and HAMD-24, as well as the equations including CD3+, CD8+, cortisol, and FACT-B, were established. BDNF was the mediating variable between CD4+ and HAMD-24. Cortisol was the mediating variable between CD3+, CD8+ and FACT-B. Neither HAMD-24 nor FACT-B could form a direct path with T lymphocytes.Conclusion: T lymphocytes may be involved in the depression of breast cancer patients since a poor quality of life could inhibit T lymphocytes, and this may be the underlying physiological cause of breast cancer-related depression.