Thanks to more accurate imaging technology, numerous reports have demonstrated that the incidence of papillary thyroid carcinoma (PTC) is increasing worldwide (1, 2). Papillary thyroid microcarcinoma (PTMC) is a subset of differentiated thyroid cancers with a favorable prognosis (3), boasting a 10-year survival rate exceeding 97% (4). Lymph node metastasis in the central compartment (CLNM) occurs in 40-60% of patients with PTMC and is a significant risk factor for tumor recurrence in PTC (5, 6). Therefore, therapeutic central compartment neck dissections (CND) are indicated in cases of clinically positive CLNM when preoperative pathology is confirmed (7–9). Micrometastases have been found in the majority of cases and have minimal impact on patient survival (10). Consequently, the necessity of prophylactic central neck dissection (PCND) remains a controversial issue in patients with clinically node-negative (cN0) PTMC. Supporters argue that routine dissection of central lymph nodes is beneficial for accurate postoperative staging and subsequent treatment guidance. As technology advances, the initial operation is conducive to thorough dissection, avoiding the challenges of complete lymph node removal due to postoperative tissue adhesion and scarring in cases of tumor recurrence, which not only affects the thoroughness of radical surgery but also easily leads to complications (11, 12). Conversely, opponents argue that there is no strong evidence to support PCND. Instead, an increasing number of clinical trials have confirmed no clear benefit on locoregional and biochemical recurrence in PCND patients, even leading to more complications (13–16). The 2015 American Thyroid Association (ATA) guidelines recommend that PCND should be considered in patients with T3–4 PTC, while the Chinese guidelines recommend ipsilateral prophylactic central lymph node dissection based on the effective protection of parathyroid glands and nerves (17). To better determine whether PCND is necessary in the surgical treatment of all PTMC, we aim to elucidate the benefits and disadvantages of PCND and the recurrence rate in cN0 PTMC patients in two groups.

With improvements in ultrasound technology, thyroid microcarcinoma continues to be discovered, and the incidence of thyroid cancer in the United States has tripled over the past 20 years (19), a similar trend has been observed in China (20, 21). PTMC is considered a relatively less biologically invasive cancer, and is even known as an indolent cancer, although it can be aggressive in some patients (22, 23). One of the most important prognostic indicators for PTMC is the presence of lymph node metastases at the initial presentation (24, 25). Micrometastases have been found in up to 80% of cases, with the central cervical compartment involved in 20%-50% of patients (20, 26). When lymph node metastases are identified preoperatively, current guidelines support therapeutic central lymph node dissection, but preoperative ultrasound and other related auxiliary examinations can only detect less than half of the metastases, leading to an underestimation of lymph node metastasis in the central area (27). PCND can provide more precise postoperative staging for PTMC, potentially changing subsequent treatment options and decreasing local recurrence rates, thus improving mortality (28, 29). Opponents argue that PCND will only increase postoperative complications such as hypoparathyroidism and recurrent laryngeal nerve injury, without impacting the long-term prognosis or reducing the recurrence risk (14–16). The need for central lymph node dissection has been thoroughly explored in numerous studies, most of which enrolled patients with PTC, and there are relatively few data focusing on PTMC. Therefore, there is currently no convincing evidence to support performing PCND in cN0 PTMC. Compared to ATA and European guidelines, Chinese experts are more inclined to perform PCND, emphasizing the importance of protecting nerves and parathyroid glands (30). Several articles have recently been published on whether to perform PCND in PTMC. Yang et al. (31)used three Cox regression models to evaluate the correlation between PCND and locoregional recurrence rate (LRR), finding no significant difference in the 15-year LRR between groups and a small absolute benefit for PTMC. Of all 1584 patients enrolled, 1484 underwent thyroidectomy plus PCND, and only 100 underwent thyroidectomy alone, creating a large disparity in enrollment numbers that limits comparability in postoperative complications. Xie et al. (32) showed that the LRR between the non-dissection group and the dissection group was 7 (2.4%) vs. 2 (1.1%), a non-significant difference (χ2 = 0.126, P = 0.169). Except for the hand and foot numbness rates (P < 0.001), which were considerably greater in the dissection group, there was no difference in the remaining postoperative complications between the two groups, such as hypoparathyroidism and hypocalcemia. Both of the above studies enrolled patients over a period of more than 10 years, with many changes in guidelines, and the results may not be very instructive. In our study, we enrolled patients for 4 consecutive years, ending no later than the 2015 ATA publication. The decision to perform PCND after total thyroidectomy is generally at the surgeon’s discretion, considering various risk factors. All of these factors have been referred to as risk factors for central lymph node metastasis in previous studies (23, 33, 34), and all the clinical-pathological markers can be assessed before and during surgery. Patients with Hashimoto’s thyroiditis often have a large number of paratracheal lymph nodes, which can easily be mistaken for metastatic lymph nodes during surgery, resulting in excessive dissection (35). Intraoperative pathological frozen section examination may be able to better identify such enlarged lymph nodes (36).

In our study, which recruited low-risk patients, there were no deaths or distant metastases, and there were only 2 (1.36%) and 5 (2.16%) cases of recurrence in the two groups, respectively. There was no statistical difference between the two groups, which aligns with previous studies (16, 31, 32, 37). Radioactive iodine therapy has played a positive role in patients with insufficient surgical treatment (38), so most studies involve iodine-131 therapy, even in low-risk patients (39). However, iodine-131 therapy requires an isolation environment (40), and none of our patients had residual cancer post-surgery, so none of them received iodine-131 therapy. Increased complications after surgery are one of the main reasons why many experts do not recommend PCND. Common complications include nerve damage, parathyroid gland injury, lymph leakage, and accidental parathyroid gland removal (41, 42). Postoperative hypoparathyroidism is divided into temporary and permanent types. Once a patient develops permanent symptoms, they need to supplement calcium and vitamin D for a long time. Occasionally, they may experience numbness in their hands and feet, which seriously affects their quality of life (43). In our study, the TT+PCND group had a significantly higher incidence of hypoparathyroidism than the TT group, and the difference was statistically significant (38.5% vs. 24.9%, P = 0.005), consistent with previous studies (13–16). The position and number of parathyroid glands are not fixed, and their appearance closely resembles that of fat and lymph nodes. Therefore, they are often misdiagnosed as lymph nodes and subsequently subjected to lymph node dissection. From our data, we can see that the TT+PCND group had a significantly higher rate of accidental parathyroidectomy (6.49% vs. 2.05%, P = 0.049). Therefore, they should not be easily removed unless there is certainty (44). Previous experts have questioned whether bilateral central lymph node dissection has more complications compared to unilateral dissection. Dobrinja et al. (13) subdivided the PCND group between ipsilateral and bilateral central neck dissection, finding no significant difference in terms of RLN injury or hypoparathyroidism. In contrast, we also divided the PCND group into bilateral and unilateral subgroups and identified that there were more cases of accidental parathyroidectomy in the bilateral cohort. Therefore, bilateral dissection must be performed with greater care to identify parathyroid glands.

We believe that there are many factors to consider when deciding whether to perform PCND for patients with cN0 PTMC. Firstly, sufficient preoperative examination and evaluation should be conducted, including high-resolution color Doppler ultrasound and thyroid enhanced CT (45). Secondly, the patient’s baseline characteristics, such as gender, age, tumor size, multiple lesions, and Hashimoto’s thyroiditis, should be considered, and the qualifications of the surgeon should be strictly standardized, as inexperienced thyroid surgeons have relatively increased complication rates (46). Thirdly, fine separation along the thyroid capsule during the operation should be performed. Due to the proximity of the lower parathyroid glands to the central lymph nodes, they are at risk of being damaged during surgery (47). Parathyroid glands should not be easily removed unless there is certainty. At the same time, it is also necessary to carefully investigate whether there are parathyroid glands that have been mistakenly removed from the excised thyroid gland and the cleared lymph nodes. If discovered, they should be transplanted in a timely manner.

Our research has limitations. Firstly, we are a retrospective study with potential selection bias between the two groups. Secondly, the patients we enrolled had a low risk of recurrence, and the recurrence rates of both groups were not high, making it difficult to make a comparison. Thirdly, we mainly rely on medical records to document complications. Incomplete records will definitely lead to underestimation of complications in some patients. Fourth, Postoperative laryngoscopy within one month may miss transient vocal cord paralysis due to potential early functional recovery, resulting in underestimated temporary paralysis rates. It is necessary to conduct large-scale multicenter longitudinal design studies to better evaluate the role of dissection in PTMC treatment.

In summary, PCND should not be applied to all PTMC patients with cN0 disease. For most extremely low-risk patients, we can assure them that the risk of recurrence will not increase without PCND, and unnecessary postoperative complications can be avoided. Our long-term follow-up data demonstrate that PCND does not improve clinical outcomes while increasing complication risks, providing compelling evidence against its routine application in low-risk cN0 PTMC.