Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignant tumors. Although neoadjuvant chemoradiotherapy combined with surgery has significantly improved the survival rate of patients with locally advanced esophageal cancer, approximately half of the patients will experience local regional recurrence or distant metastasis. Lymphocytes are crucial immune cells in the human body, playing a key role in combating infections and tumor development. In recent years, an increasing body of research has indicated that lymphocyte depletion is a significant factor associated with poor prognosis in various solid tumors, including esophageal cancer. The lymphocyte depletion caused by radiotherapy has garnered considerable attention from oncologists. However, there is still a lack of prospective clinical research data on lymphocyte protection in thoracic tumors. Therefore, this study aims to provide high-level evidence from evidence-based medicine regarding the correlation between lymphocyte depletion and prognosis in esophageal cancer patients, offering more effective strategies and methods to improve the outcomes of neoadjuvant chemoradiotherapy for esophageal cancer.

Inclusion Criteria:

1. Patients are able to understand and are willing to participate in the trial, and a signed consent form can be obtained;
2. Pathologically confirmed esophageal squamous cell carcinoma;
3. locally advanced ESCC (cT3-4 or N+);
4. the age of patients should be more than 18 years, and less than 80 years;
5. aged between 18 and 80 years;
6. KPS score of patients should be more than 80

Exclusion Criteria:

1. diagnosis of metastatic esophageal cancer;
2. Patient refuses to receive systemic drug treatment;
3. clinical diagnosis of pleural metastasis or malignant pleural effusion;
4. Pregnant or breastfeeding women;
5. Severe non-cancerous medical comorbidities that affect the implementation of radiotherapy.