Treatment with immune checkpoint inhibitors such as programmed death receptor 1 (PD-1 inhibitors) for advanced and metastatic esophageal squamous cell carcinoma (ESCC) significantly improves patients' overall survival compared to chemotherapy alone. Despite this milestone breakthrough, immunochemotherapy also has known limitations. Indeed, only 45-72% of patients achieved objective responses. It is urgent to find out easily-determined and convenient biomarkers to identify patients who will benefit from such treatment modality. Due to the luminal structure of the esophagus, the exact diameter of esophageal tumor cannot be precisely measured per RECIST 1.1. Moreover, the definition of the metastatic lymph node in which the short-axis lengths should be longer than 1.5 cm hinders the risk of missing the smaller metastatic lymph node foci. Thus, it is difficult to implement morphology-based criteria for evaluating the neoadjuvant immunochemotherapy response. The current study aimed to investigate the role of iPERCIST in predicting tumor response and the short-term overall survival of patients with locally advanced ESCC after neoadjuvant immunochemotherapy.

Inclusion Criteria:

• pathologically confirmed locally advanced ESCC (cT3-4anyNM0) that was potentially resectable after neoadjuvant immunochemotherapy.
• treatment-naïve and had the adequate cardiopulmonary function

Exclusion Criteria:

• previous autoimmune disease
• unable to complete planned treatment courses and no complete follow-up PET-CT scan

Eligible patients were selected according to the following criteria: pathologically confirmed locally advanced ESCC (cT3-4anyNM0) that was potentially resectable after neoadjuvant immunochemotherapy. All patients were treatment-naïve and had adequate cardiopulmonary function. The exclusion criteria included previous autoimmune disease; unable to complete planned treatment courses and no complete follow-up PET-CT scan.