This is a cross-sectional study. From April 2018 to December 2018, all patients with breast cancer and depression who were admitted to the Guangdong Provincial Hospital of Traditional Chinese Medicine were recruited. Information and blood samples were collected from any participants who met the inclusion criteria.
Women between 18 and 75 years old who were pathologically diagnosed with primary malignant breast tumours were considered for inclusion. Participants had to meet the DSM-5 diagnostic criteria for depressive disorders, and their HAMD-24 score needed to be between 9 and 35. All of the participants voluntarily participated after total or partial breast resection while not receiving chemotherapy.
Participants who suffered from a mental illness such as depression, mania, or suicidal tendencies before the diagnosis of breast cancer or had a family history of mental illness were excluded, as were participants who were currently taking drugs that could cause depression-like symptoms. Women who were pregnant or lactating, had high blood pressure, heart disease, hepatitis, kidney disease, or autoimmune disease were excluded.
Our study chose HAMD-24 as the primary outcome. To evaluate the impact of immune function on depression in people with breast cancer, we selected the number of T cells in the peripheral blood as a predictor of depression. In addition, hormones, neurotrophic factors, inflammation, quality of life and other factors were considered in the analysis of the onset of depression and the immune cell status. Therefore, this study collected information on HAMD-24, FACT-B, T-cell, cortisol, BDNF, and inflammatory factors.
HAMD-24 and FACT-B scales
The HAMD-24 scale is one of the most commonly used clinical scales for evaluating depression. It evaluates depression from the dimensions of somatization, weight, cognitive impairment, retardation, day and night changes, sleep disturbance, and despair. FACT-B is one of the scales of the Functional Assessment of Cancer Therapy. It is one of the main scales for assessing the quality of life of breast cancer patients. The assessment is mainly based on social and family status, emotional status, functional status, physiological status, and personal status.
In this study, peripheral blood samples were collected for T cell evaluation from participants who agreed to provide blood samples. We mainly observed the content of CD3, CD4, and CD8 cells. The collection of T cells was carried out on an empty stomach around 8:00-8:30 in the morning.
Cortisol is one of the main hormones that affects the expression of human immune function, and it has a certain inhibitory effect on T lymphocytes. The secretion of cortisol fluctuates in response to people's living conditions and stress. Therefore, this study selected subjects' fasting peripheral blood cortisol at 8:00-8:30 in the morning as the observation index.
Brain-derived neurotrophic factors promote synaptic plasticity. In depressed people, the content of peripheral blood BDNF is reduced, and the degree of depression is inversely related to BDNF. BDNF and other neurotrophic factors will also change in response to immune function. In this study, we collected BDNF from the peripheral serum of the subjects for evaluation, and the collection time was 8:00-8:30 in the morning on an empty stomach.
Inflammatory factors are highly expressed in depressed people, and there is a positive correlation between inflammatory factors and the severity of depression. We selected TNF and IL-1β for evaluation, which are closely related to tumours, as indicators of peripheral inflammation. The collection time was 8:00-8:30 in the morning on an empty stomach.
To reduce bias, we established strict inclusion criteria, selected patients who only developed mild to moderate depression after breast cancer. The time and place of data collection for all subjects were unified to ensure data consistency.
Recruitment of participants in this study was limited to breast cancer patients who were admitted to the Guangdong Provincial Hospital of Traditional Chinese Medicine from April 2018 to December 2018. All of the participants experienced their first episode of depression after a diagnosis of breast cancer. During this period, a total of 93 breast cancer patients with depression were included in this study, including 46 participants who agreed to blood testing.
All statistical analyses were performed using SPSS (IBM SPSS Statistics version 24.0) and MPLUS (version 8.0). The quantitative data are expressed as the mean ± SD and the categorical data are described in terms of quantity and proportion. Correlation analysis was performed for the HAMD-24 score, FACT-B score, BDNF, T lymphocytes, inflammatory factors, and cortisol levels of 46 participants. We chose Pearson’s or Spearman’s correlation according to the variable type and recorded the correlation coefficient between the variables. P<0.05 was considered to be statistically significant. In addition, we used a structural equations model (SEM) to test the mediation relationship among the variables. The structural equation model was developed by using MPLUS (version 8.0). The model fit was assessed with the comparative fit index (CFI, critical value≥0.9), the Tucker Lewis Index (TLI, critical value≥0.9), the root mean square error approximation (RMSEA, value blew 0.08).