Dear editor,Thank you very much for the letter (1) and the questions emerging from this study (2). These questions will be helpful for promoting scientific research progress in thermal ablation (TA) of papillary thyroid carcinoma (PTC). Our responses to the related questions are below.The first question concerns the indication that this study exceeds the existing guidelines. TA has become an important minimally invasive treatment for tumors in different locations and has gained rapid development in clinical practice. Therefore, expanding the application of TA in the treatment of PTC has become a trend of medical development. According to the existing guidelines, TA is approved for the management of T1a PTC (3). However, the existing guidelines do not mention any theoretical or clinical evidence that TA cannot be used to treat T1b PTC. In clinical practice, for T1b PTC patients who cannot tolerate or refuse surgery due to physical conditions or concern regarding hypothyroidism and scars after surgery, TA provides a possible alternative option. A retrospective analysis of the clinical data from these cases could provide preliminary research on the safety and effectiveness of TA for T1b PTC.Regarding the relationship between the tumor and thyroid capsule, the American Joint Committee on Cancer TNM staging system for differentiated thyroid cancer classified PTC close to the capsule as T3N0M0. However, the updated guidelines pointed out that minor extrathyroidal extension identified only by histologic examination was no longer a variable in determining the T category (4). The results of our latest study also showed that TA is safe and effective for PTC close to the thyroid capsule (5). PTC with extrathyroidal invasion was excluded from the present study. Thus, there is no need to include the description of the distance between the tumor and the capsule.Tumor treatment is divided into preoperative staging and postoperative staging, and the surgical strategy mainly depends on preoperative staging. For PTC, preoperative staging is mainly based on imaging examinations such as ultrasound and computed tomography. However, it is difficult to identify microfoci or micrometastases that cannot be detected by imaging. Microfoci and micrometastases are problematic for both TA and surgery. However, microfoci and micrometastases may not always form visible lesions, which are mainly attributed to immune suppression. Moreover, several studies have shown that microfoci and micrometastases do not play a key role in tumor progression (6, 7). The results of our study showed that the rate of postablation lymph node metastasis was only 0.6% in the follow-up period, indicating that the possible presence of microfoci or micrometastases did not influence the tumor progression rate during the follow-up period.Both microwave ablation (MWA) and radiofrequency ablation (RFA) are methods of TA, sharing similar principles and the same treatment procedures. This study enrolled patients treated by MWA or RFA, and there were no differences between MWA and RFA in terms of tumor disappearance or complication rates (P = .15 and P = .96, respectively). Indeed, this is a retrospective multicenter study, and it is impossible to set the application criteria for MWA or RFA in advance. We can only describe the objective fact: the selection of MWA or RFA depends on the preferences of different radiologists. Regarding the power settings of the MWA and RFA, the range of power usage is provided in the Methods section. Moreover, the key point of evaluating the application prospect of a technique is the safety and efficacy which was demonstrated by the objective results provided in the present study.