P198. Tumor Regression Grade as Predictor of Adjuvant Therapy Benefits in Patients with Esophageal Squamous Cell Carcinoma after Neoadjuvant Therapy: A Multicenter Retrospective Study

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Background
Neoadjuvant therapy followed by surgery is preferred for locally advanced esophageal squamous cell carcinoma (ESCC), but the necessity of adjuvant therapy remains controversial. Tumor regression grade (TRG) reflects the response to neoadjuvant therapy and may predict patient prognosis, yet its role in guiding adjuvant therapy remains unexplored. This study aimed to explore the role of TRG and other clinical characteristics in predicting the efficacy of postoperative adjuvant therapy in ESCC patients receiving neoadjuvant therapy.
Methods
This study included patients who underwent R0 esophagectomy for thoracic ESCC after neoadjuvant therapy between January 2016 and December 2021 across three high-volume centers. Patients were assessed by TRG and divided into good responders (TRG 0-1) and poor responders (TRG 2-3).
Results
Among 416 patients with a median follow-up of 52 months, adjuvant therapy extended median survival by 8 months, which was statistically insignificant (p=0.28). The 3-year and 5-year OS rates were 68.2% and 58% in the adjuvant therapy group, compared to 64.8% and 54% in the observation group. In the TRG 0-1 subgroup, those receiving adjuvant therapy had 3-year and 5-year OS rates of 94.6% and 86.8%, compared to 78.8% and 71.6% for the observation group (P = 0.02). Multivariable Cox regression showed adjuvant therapy was associated with reduced mortality in the TRG 0-1 (HR 0.32; 95% CI 0.14-0.73; P = 0.006), positive lymph nodes (HR 0.53; 95% CI 0.36-0.78; P = 0.001), and ypT3-4 subgroups (HR 0.63; 95% CI 0.43-0.92; P = 0.017).
Conclusions
TRG is a promising predictor of the prognostic value of adjuvant therapy in ESCC patients. Patients with a good TRG response, positive lymph nodes and ypT3-4 stage benefit from adjuvant therapy.

Authors
yizhou huang (1), Maohui Chen (2), Chun Chen (3), Bin Zheng (2)
Institutions
(1) Fujian Medical University Union Hospital, Fujian, (2) Fujian Medical University Union Hospital, China, (3) Fujian Medical University Union Hospital, Fu Zhou, Fujian