Comment on “The role of thymus preservation in parathyroid gland function and surgical completeness after bilateral central lymph node dissection for papillary thyroid cancer: a randomized controlled study”

Dear Editor, Papillary thyroid carcinoma often metastasizes to ipsilateral cervical lymph nodes[1]. During central compartment lymph node dissection, preserving the thymus is considered to help reduce the risk of accidentally removing the parathyroid glands or damaging their blood supply, thereby decreasing postoperative hypocalcemia. However, although thymic metastasis is relatively uncommon in papillary thyroid carcinoma, it does carry a certain risk of occurrence. Therefore, the practice of thymus preservation remains controversial regarding oncological radicality[2]. Recently, we noted a study by Qiu et al[3], which explored the impact of thymus preservation on parathyroid function and surgical completeness during total thyroidectomy combined with bilateral central lymph node dissection. The study aimed to provide evidence for managing the thymus during bilateral central lymph node dissection in patients with bilateral papillary thyroid carcinoma, hoping to reduce parathyroid-related complications while ensuring oncological safety, thereby optimizing surgical planning and improving patients’ postoperative quality of life. However, several aspects of the study’s design and reporting warrant discussion. This correspondence was developed following the TITAN Guidelines 2025(2) for the declaration and use of artificial intelligence in scholarly publishing. No AI tools were employed in the conception, design, analysis, interpretation, or writing of this work[4]. First, the randomization was conducted after completing total thyroidectomy and obtaining frozen pathology results. However, central compartment lymph node dissection is a continuous anatomical procedure, and the handling of the inferior thymic region should be consistent with the superior and central portions. If grouping is performed after thyroid removal and partial dissection of the superior and central regions, non-random differences in tissue structure, vascular distribution, and surgical planes in this area may arise between the two groups. Such differences could affect the protection of parathyroid blood supply and the thoroughness of lymph node dissection, thereby compromising comparability between groups. A more rigorous approach would involve completing randomization after anesthesia induction but before surgery begins, ensuring that the entire procedure strictly follows the established protocol. Second, only 20.4% of patients (11 cases) in the study received radioactive iodine therapy and had stimulated thyroglobulin measured. Conducting intergroup comparisons with such a small sample (seven cases in the thymus-preserving group and four cases in the thymus-resecting group) lacks sufficient statistical power. Any conclusion of “no difference” may be a false negative due to the limited sample size. Therefore, relying on these results as evidence for oncological safety has methodological limitations. Third, the definition of the key procedure “thymic upper pole resection” is vaguely described. The study only mentions resecting the “thyrothymic ligament” without clarifying its anatomical boundaries, such as the relationship with the thyroid inferior pole cranially, whether the thymic body is involved caudally, the lateral limits with the carotid sheath, and whether the surrounding fatty-lymphatic tissue should be dissected en bloc. Given that the thymic region is a common site for metastasis of anterior mediastinal lymph nodes, the lack of clear procedural definition weakens the conclusion that “oncological safety was unaffected” and hinders the reproducibility and application of this technique across different medical centers. Fourth, the study mentions autotransplantation of completely devitalized parathyroid glands but does not report the implementation rate between the two groups, the number of glands transplanted, the transplantation sites, or functional recovery outcomes. Parathyroid autotransplantation is an important means of postoperative functional recovery, but its function often takes weeks to months to fully establish. If the thymus-resecting group underwent more transplants due to more severe in situ gland damage, their lower early postoperative parathyroid hormone levels might reflect the delayed function of the transplanted glands rather than the direct impact of thymus resection on blood supply. Failing to report and analyze this variable may affect the accurate interpretation of the study results. Despite these issues, the study provides preliminary clinical insights into whether to preserve the thymus during total thyroidectomy combined with bilateral central lymph node dissection in patients with bilateral papillary thyroid carcinoma. It contributes to future efforts to refine surgical strategies while ensuring oncological safety.