This clinical trial aims to determine whether perioperative goal-directed nutritional therapy can prevent postoperative pulmonary and other major complications in malnourished esophageal squamous cell cancer patients. Its main question is whether individualized nutritional therapy can improve short-term surgical outcomes and long-term prognosis. Researchers will compare goal-directed and conventional nutritional therapy to identify differences in morbidities and survival.

Severe malnutrition is a significant risk factor for postoperative complications in esophageal cancer patients. Early oral nutritional supplementation after surgery can prevent weight loss and improve quality of life. The EFFORT trial showed that individual-based enteral nutrition support reduced complications, extended 1-year survival, and improved quality of life. This study aims to assess the safety and effectiveness of individualized perioperative nutrition support guided by daily energy targets in esophageal cancer patients at nutritional risk. It also seeks to determine if supplementing immunonutrition can effectively reduce postoperative complications. This study was conducted as a multicenter, open-label, randomized, controlled phase 3 trial. The experiment group was administered goal-directed enteral nutritional therapy, while the control group received conventional enteral nutritional therapy. The study observed the participants' major pulmonary and other complications within 90 days post-surgery and nutritional status, disease-free survival (DFS), and overall survival (OS) in both groups.

Inclusion Criteria:

1. Aged 18-80 years old;
2. ECOG PS 0~1;
3. NRS 2002 score ≥3;
4. Malnutrition diagnosed according to the GLIM criteria;
5. Histopathologically confirmed as esophageal squamous cell carcinoma;
6. Primary tumors located in thoracic esophagus;
7. Resectable locally advanced disease with clinical stage II to IVA (8th edition UICC/AJCC) evaluated by a multidisciplinary team;
8. Neoadjuvant therapy will be administered, which may entail preoperative chemo-radiotherapy, chemotherapy only, or a combination of immunotherapy such as anti-PD-1/PD-L1;
9. Informed consent for random assignment and completion of the protocol.

Exclusion Criteria:

1. NRS 2002 score < 3;
2. Upfront surgery without neoadjuvant treatment;
3. Any comorbidity interferes with the digestion and absorption of ORAL IMPACT®;
4. Receiving any other nutritional support during the study;
5. Unable to consume nutrition orally or receive it through tube feeding before surgery;
6. History of other malignancies in the past 5 years, except successfully treated basal-cell skin carcinoma and cervical tumors in situ;
7. Severe abnormalities of liver and kidney functions (ALT≥2 times the upper limit of normal; Total bilirubin Tbil≥2 upper limit of normal; Creatinine Cr≥2 upper limit of normal);
8. Metabolic disorders, including uncontrolled diabetes mellitus or fasting blood glucose ≥10mmol/L, hypothyroidism, or hyperthyroidism;
9. Receiving fat emulsion containing Omega-3 fatty acids, glutamine, thymosin, glucocorticoid, thyroxine, growth hormone, and anti-tumor necrosis factor biologic agents
10. History of known allergy to any component of ORAL IMPACT®;
11. Pregnant or lactating women, women of childbearing potential with either a positive pregnancy test at baseline or not using a reliable and appropriate contraceptive method;
12. Refuse to sign the consent or unable to follow the study protocol;
13. Inappropriate to participate in this study judged by investigators.