Predictors of impaired effectiveness of carbon nanoparticle-based central lymph node tracing in patients who underwent surgery for papillary thyroid cancer: A retrospective cohort study

Carbon nanoparticles (CNs) are used in papillary thyroid cancer (PTC) surgery to facilitate central lymph node dissection (CLND) and protect the parathyroid glands (PGs). However, some cases develop hypoparathyroidism after using CNs. This cohort study was undertaken to explore the predictors of the reduced effectiveness of CNs. Data on patients with PTC who underwent surgery wherein CNs were used during CLND were reviewed retrospectively. Patients who did not develop hypoparathyroidism and developed hypoparathyroidism were classified into Group A and B, respectively. Demographic and clinical characteristics were compared between the 2 groups. Univariate and multivariate logistic regression analysis were performed on related variables. The receiver operating characteristic curve was used to evaluate the predictors of the binary logistic model and the cutoff value of each predictor was obtained. A total of 265 patients were included. Compared with Group A, the patients in Group B had a higher body mass index (BMI) (P = .003), were more frequently associated with Hashimoto thyroiditis (HT) (P = .001), and tumors were larger in size (P = .026). Multivariate logistic regression analyses were performed on these variables and showed that HT (P = .001) and tumor size (P = .001) predicted the impaired role of CNs. CNs are not always useful in protecting PG function in patients who undergo CLND for PTC. In patients with coexisting HT (blood thyroid peroxidase antibody [TPOAb] level higher than 44.0 IU/mL or blood anti-thyroglobulin antibody [ATG] level higher than 125.0 IU/mL) or a tumor size exceeding 1.1 cm in diameter, the protective role of CNs may be impaired.