Effects of TDCS Intervention on Neoadjuvant Chemotherapy in Breast Cancer Patients with Mild to Moderate Depression

Stress is the non-specific physiological and psychological response of the body to various stressors. Previous studies have proven that chronic stress is a recognized risk factor of tumors, participating in multiple stages such as tumor occurrence, development, metastasis, recurrence, and drug resistance. Epidemiological studies show that cancer patients often have chronic mental stress, accompanied by cognitive impairment, symptoms of depression and anxiety, and these patients have a poorer prognosis. Depression and anxiety are also associated with higher incidence of tumors, cancer-specific mortality, and all-cause mortality. Breast cancer has become the most common malignant tumor in women, accounting for about 30% of new cancer cases in women. Since 1991, the mortality rate of breast cancer in women worldwide has slowed down due to the rapid development of screening and early diagnosis and treatment methods. It is worth noting that in China, breast cancer is still the leading cause of cancer in women, and its mortality rate is still on the rise. Compared with patients with other types of cancer, breast cancer patients often accompany physical damage, changes in physiological status, decline in quality of life, sensitivity in interpersonal relationships, and side effects of drug treatment during the occurrence, development, and treatment of cancer, leading to long-term chronic mental stress. The prevalence of depression and anxiety in early-stage breast cancer patients in China is as high as 44.1% and 35.2%, respectively. A meta-analysis based on 282,203 breast cancer patients suggests that depression is related to breast cancer-specific mortality, and patients with breast cancer and depression have a poorer prognosis. Intervention in response to stressors may improve psychological and physiological adaptation processes and even benefit quality of life and clinical health outcomes. More and more randomized controlled trials focus on improving the quality of life and adverse reactions of cancer patients after stress management, but there are few reports on the direct improvement of anti-tumor efficacy. This evidence proves that stress factors should not be ignored in the clinical process of tumor prevention and treatment. Our clinical practice has found that in addition to drug treatment, psychological and physical therapies are also effective for stress disorders. Therefore, we plan to conduct a small sample, exploratory, randomized controlled study to clarify the impact of transcranial direct current stimulation (tDCS) intervention on the efficacy of neoadjuvant chemotherapy in breast cancer patients with depressive symptoms. Newly diagnosed breast cancer patients will be assessed for emotions by mental health professionals, with a PHQ9 score of 5-14 and ≥ 5 symptoms considered positive, combined with enrollment criteria for screening. Patients who meet the enrollment criteria will be randomly divided into the control group (i.e., supportive psychotherapy group) and the experimental group (i.e., tDCS + supportive psychotherapy group). Both the experimental and control groups will receive supportive psychotherapy during the treatment process (mainly to provide psychological support for patients). The primary study endpoint is the objective remission rate (ORR) of neoadjuvant treatment, and the secondary study endpoints include pathological complete remission rate (pCR), improvement in depression scores (HAMD score changes), changes in breast-specific gamma imaging (BSGI), quality of life assessment after neoadjuvant chemotherapy, and ERP event-related potential detection. In addition, further exploratory research will be carried out, with stratified analysis based on breast cancer molecular typing, population characteristics, immune components, and changes in hormone levels. This study aims to improve the depressive state of breast cancer patients undergoing neoadjuvant chemotherapy through physical therapy (tDCS) and to clarify whether there is a correlation between emotional intervention and neoadjuvant efficacy.