Neoadjuvant Immunotherapy Combined With Chemotherapy Sequenced With Endoscopic Resection for Esophageal Cancer (Endosurgery-02)

Cohort A - Potentially resectable ESCC: Inclusion Criteria： 1. Age range: 18-80 years old; 2. Patients diagnosed with esophageal squamous cell carcinoma (ESCC) through histopathological examination of biopsy tissues from the primary tumor; 3. Patients with potentially resectable esophageal cancer confirmed by imaging and endoscopic examinations (T1b-3, N0, M0, with a tumor size not exceeding 5 cm and occupying less than 2/3 of the luminal circumference); Patients who have not received any antitumor treatment, including but not limited to surgery, radiotherapy, chemotherapy, immunotherapy, and targeted therapy; 4. Patients with a preoperative Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1; 5. Patients with a preoperative American Society of Anesthesiologists (ASA) physical status classification of I-III; 6. Female patients of reproductive age should have a negative pregnancy test and be willing to use effective contraceptive methods during the study period; 7. Patients who have signed the informed consent form. Exclusion Criteria: 1. Patients with potential tracheoesophageal fistula or aortoesophageal fistula; 2. Patients with severe malnutrition or requiring tube feeding; 3. Patients with other malignancies that have not been cured within the past 2 years (except for cured basal cell carcinoma of the skin and cured carcinoma in situ of the cervix); 4. Patients with active autoimmune diseases or a history of autoimmune diseases or symptoms that require systemic corticosteroid treatment or anti-autoimmune drug therapy; 5. Immunocompromised patients, or patients who are still receiving systemic steroids (prednisone \> 10 mg/day or equivalent) or other forms of immunosuppressive therapy within 7 days before the first dose of neoadjuvant therapy in this study; 6. Patients with active infections requiring systemic treatment within 7 days before the first neoadjuvant therapy in this study; 7. Patients with a history of allogeneic organ or stem cell transplantation; 8. Patients with allergies to drugs or related components involved in this study; 9. Patients who are currently participating in any other clinical study. Cohort B - Surgery-contraindicated ESCC: Inclusion Criteria: 1. Individuals aged above 18 years; 2. Patients diagnosed with esophageal squamous cell carcinoma through histopathological examination of biopsy tissues from the primary tumor; 3. Patients with esophageal cancer deemed as surgically contraindicated (including those with cervical esophageal cancer, surgical contraindications, those who refuse surgery, or those considered high-risk for esophagectomy, defined as having at least one of the following characteristics: (1) age over 75 years, (2) Charlson comorbidity index \>= 2, (3) presence of moderate lung dysfunction, (4) malnutrition (with a body mass index below 18 kg/m\^2)), with a clinical staging of cT1b-3N0M0, a tumor size not exceeding 5 cm, and occupying less than 2/3 of the luminal circumference; 4. Patients who have not undergone any antitumor treatment, including but not limited to surgery, radiotherapy, chemotherapy, immunotherapy, and targeted therapy; 5. Female patients of reproductive age should have a negative pregnancy test and be willing to adopt effective contraceptive measures during the study period; 6. Patients who have signed the informed consent form. Exclusion Criteria: 1. Patients with allergies to the drugs or related components involved in this study; 2. Patients who are currently participating in any other clinical study.