Objective To investigate the correlation between the B-Raf proto-oncogene, serine/threonine kinase (BRAF) ^V600E mutation and the clinical characteristics of papillary thyroid cancer (PTC), and to assess its significance and value in evaluating the efficacy of ¹³¹I therapy.

Methods A retrospective analysis was conducted on the clinical data of 291 PTC patients who underwent ¹³¹I therapy at our hospital from April 2018 to April 2023. Based on the results of the BRAF^V600E genetic test, the patients were divided into the BRAF^V600E mutation group and the BRAF^V600E wild-type group. According to the 2021 guidelines for the efficacy classification of ¹³¹I therapy in differentiated thyroid cancer, patients were classified into four groups: excellent response (ER), indeterminate response (IDR), biochemical incomplete response (BIR), and structural incomplete response (SIR). The correlation between BRAF^V600E mutation, other factors, and the invasiveness and efficacy of PTC was analyzed using independent sample t-test, Mann-Whitney U test, Kruskal-Wallis test, and chi-square test. Logistic regression analysis was used to identify factors influencing BRAF^V600E gene mutation and efficacy evaluation.

Results The mutation group had a higher proportion of males and a lower probability of vascular invasion compared to the wild-type group (χ2=6.55, 10.94; P=0.007, 0.004). Wild-type group had higher N stages and were more likely to develop distant metastases (χ2=15.41, 16.25; P=0.000, 0.001). The proportion of patients achieving ER at 1 year was significantly higher in the mutation group, while the proportion achieving SIR was significantly lower compared to the wild-type group (χ2=8.79; P=0.032). The probability of BRAFV600E gene mutation in male PTC patients was twice that of females (OR: 1.910, 95% CI: 0.228-0.832; P=0.012). In the 6-month efficacy evaluation, for each month increase in the interval between 131I therapy and surgery, the probability of achieving SIR compared to ER increased by a factor of 1 (OR: 1.081, 95% CI: 1.014-1.153; P=0.017). In the 3-year efficacy evaluation, for each year increase in age, the probability of achieving BIR compared to ER increased by a factor of 1 (OR: 1.162, 95% CI: 1.001-1.349; P=0.048).

Conclusions Gender is the sole independent risk factor associated with the BRAF^V600E mutation. There is no clear correlation between BRAF^V600E gene mutation and greater invasiveness or poorer curative effect of PTC. Age is a critical determinant of mid-term therapeutic efficacy. When wound healing is satisfactory, the interval between ¹³¹I therapy and surgery should be minimized to achieve better short-term efficacy.