Objective To investigate the factors in fluencing thyroid function abnormality (TFA) and its relationship with the clinical efficacy of sindilizumab treatment in patients with advanced gastric cancer.

Methods The clinical data of 180 patients with advanced gastric cancer treated with sintilimab at Jinan People's Hospital from January 2021 to June 2024 were retrospectively reviewed. Patients were assigned into the TFA group and the normal control group according to thyroid function. Factors influencing the occurrence of TFA were investigated using the χ² test and multifactorial Logistic regression. Kaplan-Meier analysis and the Log-rank test were used for comparison between groups. Univariate and multivariate Cox regression were used to assess the correlation between TFA and therapeutic efficacy.

Results A total of 52 patients developed TFA. Univariate analysis showed that history of thyroid nodule, treatment regimen, liver metastasis, and carcinoembryonic antigen (CEA) were associated with the development of TFA. Multifactorial Logistic regression analysis showed that history of thyroid nodule, treatment regimen, and CEA were independent risk factors for the development of TFA (P<0.05). The objective response rate (ORR; 34.6% vs. 14.1%, P=0.002), disease control rate (DCR; 69.2% vs. 59.8%, P=0.024), and 1-year survival rate (59.6% vs. 28.9%, P=0.012) were all better in the normal control group than those in the TFA group. Cox regression analysis showed that occurrence of TFA, liver metastasis, and ≥6 treatment cycles were all independently associated with progression-free survival and overall survival in patients with advanced gastric cancer (P<0.05).

Conclusions History of thyroid nodule, treatment regimen, and CEA may influence the occurrence of TFA. TFA may be a potential predictor of the efficacy of sindilizumab therapy for advanced gastric cancer, with patients who develop TFA potentially having better treatment outcomes.