Efficacy evaluation and influencing factor analysis of postoperative (131)I for the treatment of primary hyperthyroidism combined with differentiated thyroid cancer (DTC)—a retrospective cohort study

BACKGROUND: (131)I treatment is one of the important methods of comprehensive postoperative treatment for patients with hyperthyroidism complicated with differentiated thyroid cancer (DTC). Early identification of patients with poor treatment efficacy of (131)I is particularly important. Current studies mainly focus on the relationship between hyperthyroidism and the occurrence and development of DTC, and there are few studies on the factors affecting the curative effect. The purpose of this study was to find the influencing factors of efficacy evaluation and provide evidence for early identification of patients with poor efficacy in DTC combined with primary hyperthyroidism patients. METHODS: This was a retrospective analysis of DTC patients with primary hyperthyroidism who received (131)I treatment in our department from 2012 to 2021. Follow-up intervals were 3 months within 1 year, 6 months within 1 to 2 years, and annual follow-up thereafter, the median follow-up time was 12.0 (3.0, 24.0) months. Serological examination and imaging examination were used to evaluate the efficacy. Patients were classified into an excellent response (ER) group and a non-ER group based on treatment response more than 6 months after (131)I treatment. Univariate analysis and multivariate logistic regression analysis were performed on the basic clinical characteristics, pathological characteristics and curative effect of the patients, in order to find independent risk factors affecting the curative effect. RESULTS: Eighty-nine patients were mostly female (80.9%), the average age was 43.47±11.88 years old, and tumor size was 1.2 (0.75, 1.80) cm, 56 patients (62.9%) in the ER group. psTg [odds ratio (OR): 1.325; 95% confidence interval (CI): 1.135–1.547; P<0.001], maximum tumor diameter (OR: 2.428; 95% CI: 1.392–4.235; P=0.002) and pathology-confirmed combined HT (OR: 8.669; 95% CI: 1.877–40.038; P=0.006) were independent risk factors for predicting ER. CONCLUSIONS: Our findings demonstrate that most hyperthyroidism combined with DTC patients could get favorable clinical outcomes from (131)I treatment. The tumor diameter, pathology-confirmed diagnosis of combined HT, and psTg level can be used to identify patients who can get ER by the effect of (131)I in hyperthyroidism combined with DTC at an early stage.