Objective  To identify the clinical characteristics, influencing factors, and their correlations with the efficacy of immunotherapy, with regards to thyroid function abnormalities (TFAs), in patients with advanced upper gastrointestinal tumors.

Methods Clinical data of 102 patients with advanced upper gastrointestinal tumors, who were diagnosed with TFAs and received immunotherapy at The First Affiliated Hospital of Xinjiang Medical University between January 2019 and April 2024, were retrospectively analyzed. According to the thyroid function, assigned into TFA group and normal group. The χ² test and multifactorial Logistic regression were used to explore the factors that influenced TFAs. Single-factor and multifactor Cox regression analyses and Kaplan-Meier curves were employed to examine the correlation between TFA and therapeutic efficacy.

Results Altogether, 43 patients (38.23%) developed TFAs, with a median time to occurrence of 5.36 months. Multifactorial Logistic regression analysis revealed that liver metastasis, the number of previous combination therapy regimens, and carcinoembryonic antigen (CEA) levels were factors influencing the occurrence of TFAs (P< 0.05). The objective response rate (ORR) (39.53% vs. 6.78%, P< 0.001) and disease control rate ( DCR) (72.09% vs. 35.59%, P< 0.001) were higher in the TFA group than in the control group. Cox regression analysis showed that TFAs were an influencing factor for efficacy (P< 0.05), with patients in the TFA group having significantly prolonged 1-year survival rates compared to those of patients with normal thyroid function (90.70% vs. 79.66%).

Conclusions Liver metastasis, the number of previous combination therapy regimens, and CEA levels may influence the occurrence of TFAs, which could predict the efficacy of the immunotherapy. The presence of TFAs may indicate a better therapeutic outcome for patients with advanced upper gastrointestinal tumors undergoing immunotherapy.