Image-Guided Thyroid Ablation versus Surgery for T1N0M0 Papillary Thyroid Carcinoma: A Consensus-Aligned Systematic Review and Meta-Analysis

Abstract

Image-guided thyroid ablation (IGTA), including radiofrequency ablation, microwave ablation, and laser ablation, has emerged as a minimally invasive, organ-sparing treatment strategy for carefully selected patients with low-risk papillary thyroid carcinoma (PTC) and selected patients with recurrent differentiated thyroid carcinoma (DTC). Although accumulating evidence supports favorable local tumor control and low procedure-related morbidity, comparative oncologic and safety outcomes relative to surgery require standardized synthesis using internationally accepted IGTA terminology and reporting criteria. This study aimed to compare IGTA with surgery for T1N0M0 PTC using consensus-aligned terminology, efficacy definitions, and complication reporting. Evidence regarding recurrent DTC is summarized only as contextual clinical background rather than as the primary focus of the meta-analysis. A systematic review and meta-analysis comparing IGTA with surgery for T1N0M0 PTC was conducted using the PubMed, Scopus, and Web of Science databases through June 2026. Outcome definitions, volume-related efficacy measures, and complication categories were aligned with the international consensus statement on IGTA and the PRISMA reporting recommendations. The meta-analysis showed that the odds of overall complications were significantly higher after surgery than after ablation [odds ratio (OR) = 2.75, 95% confidence interval (CI) 1.79-4.22]. No significant between-group differences were observed in tumor progression (OR = 0.81), lymph node metastasis (OR = 0.99), or overall hoarseness (OR = 1.20). However, surgery was associated with significantly lower odds of recurrence (OR = 0.64, 95% CI 0.42-0.97) but higher odds of permanent hoarseness (OR = 2.24) and transient hypoparathyroidism (OR = 5.67). In patients with recurrent DTC, ablation provided significant clinical benefits, including marked reductions in lesion volume and serum thyroglobulin levels. IGTA is a promising, minimally invasive, organ-sparing treatment option for selected patients with T1N0M0 PTC. In the present analysis, surgery was associated with lower odds of recurrence, whereas IGTA was associated with lower procedure-related morbidity, particularly lower rates of overall complications, permanent hoarseness, and transient hypoparathyroidism. Therefore, IGTA should be considered within a multidisciplinary, patient-centered decision-making framework rather than as a universal replacement for surgery. Longer-term prospective comparative studies and standardized registries are needed to determine long-term oncologic equivalence.

INTRODUCTION

Thyroid cancer remains the most common endocrine malignancy, with its global incidence increasing steadily over recent decades.¹ This trend is driven primarily by the widespread use of high-resolution ultrasonography and advanced imaging modalities, which have substantially increased the detection of early-stage, small intrathyroidal tumors, particularly papillary thyroid microcarcinomas [(PTMCs); ≤ 1 cm].^{2, 3} Despite this increase in diagnoses, disease-specific mortality has remained reassuringly stable.¹ Consequently, although these advanced imaging techniques and fine-needle aspiration biopsies have improved the early detection of PTMCs, they have also raised concerns regarding the potential overtreatment of these frequently indolent lesions.²

The management of thyroid cancer has undergone a significant paradigm shift. Because most PTMCs are slow-growing and associated with an excellent disease-specific prognosis, active surveillance has been proposed as a safe alternative to immediate surgery for carefully selected patients to reduce overtreatment.^{4, 5, 6, 7} Treatment selection should be individualized rather than standardized, taking into account tumor size and location, sonographic risk features, nodal status, comorbidities, surgical risk, patient preferences, and the psychosocial burden associated with surveillance.^{4, 5, 7, 8}

Although surgery remains the standard treatment for differentiated thyroid carcinoma (DTC), even lobectomy is associated with clinically relevant risks, including hypoparathyroidism, recurrent laryngeal nerve injury, postoperative voice changes, and the potential need for lifelong thyroid hormone replacement therapy.^{4, 5, 9} Reoperative procedures for locoregional recurrence may further increase surgical morbidity because of scar tissue, distorted anatomy, and the close proximity of the recurrent laryngeal nerve and parathyroid glands.^{9, 10, 11, 12, 13} These limitations, together with patient concerns regarding recovery, scarring, and quality of life, have increased interest in minimally invasive, organ-preserving alternatives to surgery.^{14, 15}

Active surveillance, first pioneered in Japan and subsequently adopted in the United States, has emerged as a safe management strategy for appropriately selected patients with PTMC, with long-term studies demonstrating low rates of tumor growth and lymph node metastasis.^{6, 7} However, persistent patient anxiety about living with an untreated malignancy and the need for meticulous lifelong follow-up have created a demand for alternative treatment strategies. Image-guided thyroid ablation (IGTA) techniques, particularly radiofrequency ablation (RFA) and microwave ablation (MWA), have gained considerable attention.

Pioneering work from Italy in the early 2000s using percutaneous laser ablation,¹⁶ followed by extensive clinical experience with RFA in South Korea,^10-13,17-22 established the foundation for the current evidence base. Subsequent multicenter studies from China and Europe have further supported the safety and clinical feasibility of these techniques.^{14, 23, 24, 25, 26, 27, 28} More recently, MWA has emerged as a promising modality, demonstrating favorable outcomes in the management of both benign and malignant thyroid lesions.^{29, 30, 31, 32, 33}

IGTA, primarily including RFA and MWA, has emerged as a minimally invasive treatment option for selected patients with thyroid cancer.^{22, 29} Growing evidence from long-term and multicenter studies suggests that these modalities provide favorable local tumor control while potentially reducing treatment-related morbidity and preserving thyroid function in patients with PTMC and recurrent DTC.^{30, 31} Accordingly, recent clinical guidelines and expert consensus statements have recognized IGTA as a potential therapeutic option for carefully selected patients with low-risk T1N0M0 papillary thyroid carcinoma (PTC), particularly those who are unsuitable for surgery, decline surgical treatment, or experience substantial anxiety associated with active surveillance.^{14, 22}

Although the efficacy and safety of IGTA have been increasingly reported in selected patient populations, a comparative meta-analysis remains clinically important. The key question is not whether IGTA can achieve local tumor control in isolation but how its recurrence risk and complication profile compare with those of surgery when standardized outcome definitions are applied. Furthermore, definitions of progression, recurrence, lymph node metastasis, volume response, and procedure-related complications vary across primary studies, limiting direct comparisons. Therefore, we conducted a consensus-aligned systematic review and meta-analysis comparing the oncologic and clinical outcomes of IGTA and surgery in patients with T1N0M0 PTC, with particular emphasis on recurrence, progression, lymph node metastasis, voice-related outcomes, hypoparathyroidism, and overall complications.^{15, 23, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48}

MATERIALS AND METHODS

Study selection was performed in accordance with the PRISMA 2020 recommendations.⁴⁹ PubMed, Scopus, and Web of Science were searched through June 2026, and eligible comparative clinical studies evaluating T1N0M0 PTC treated with IGTA or surgery were screened for inclusion. The detailed study selection flow diagram and the baseline characteristics of the included studies are presented in Figure 1 and Table 1.

Figure 1.

PRISMA flowchart for the meta-analysis comparing image-guided thyroid ablation with surgery in T1N0M0 papillary thyroid carcinoma. PTC, papillary thyroid carcinoma; RFA, radiofrequency ablation; MWA, microwave ablation.

TABLE 1. Baseline Characteristics of Studies Included in the Meta-Analysis Comparing Image-Guided Thyroid Ablation with Surgery.

Study (first author)	Ablation modality	Year	Study design	Ablation (n)	Surgery (n)	Total (n)
Li et al.37	MWA vs. Surgery	2019	Retrospective	168	143	311
Zhou et al.47	Laser vs. Surgery	2019	Retrospective	36	45	81
He et al.36	RFA vs. Surgery	2021	Retrospective	94	110	204
Wang et al.40	MWA vs. Surgery	2021	Retrospective	63	83	146
Xiao et al.42	RFA vs. Surgery	2021	Retrospective	91	91	182
Wei et al.41	MWA vs. Surgery	2022	Retrospective	350	350	700
Yan et al.43	RFA vs. Surgery	2023	Retrospective	44	53	97
Zheng et al.31	MWA vs. Surgery	2023	Prospective	92	106	198
Gong et al.34	RFA vs. Laser vs. Surgery	2024	Prospective	73	89	162
Guo et al.35	MWA vs. Surgery	2024	Prospective	52	71	123
Zhao et al.45	MWA vs. Surgery	2024	Retrospective	229	453	682
Wang et al.39	RFA vs. Surgery	2025	Retrospective	60	65	125
Yu et al.44	MWA vs. Surgery	2025	Prospective	100	101	201
Dou et al.32	MWA vs. Surgery	2026	Prospective	444	439	883
Fei et al.33	MWA vs. Surgery	2026	Retrospective	175	289	464
Sun et al.38	RFA vs. Surgery	2026	Retrospective	55	70	125
Zhou et al.15	RFA vs. Surgery	2026	Retrospective	150	150	300

RFA, radiofrequency ablation; MWA, microwave ablation; LA, laser ablation.

Definitions of outcomes and included population

For this analysis, the T1N0M0 population included both T1a PTMC (≤ 1 cm) and T1b tumors (> 1 cm to ≤ 2 cm), reflecting the expanding application of IGTA in contemporary comparative studies.^{15, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47} In accordance with the international IGTA consensus statement, tumor size was recorded as three orthogonal diameters whenever available, and tumor volume was calculated using the ellipsoid formula: V = πabc/6 (equivalent to length × width × height × 0.524). The volume reduction ratio (VRR) was calculated as [(initial volume-follow-up volume)/initial volume] × 100.⁴⁸ Complete ablation was defined as the absence of residual viable tumor or enhancement/vascularity within the treated target lesion. Local tumor progression was defined as persistent or newly developed viable tumor within or immediately adjacent to the treated area, whereas recurrence was defined as the development of a new malignant lesion in the thyroid remnant, contralateral lobe, or cervical lymph nodes after initial treatment success. Procedure-related adverse events were classified as major or minor according to the consensus framework, whereas voice changes and hypoparathyroidism were categorized as transient or permanent based on the definitions used in the included studies.^{14, 21, 22, 48}

Statistical analysis

A separate meta-analysis was performed for each dichotomous outcome. Comparisons were conducted to evaluate differences between the surgery and ablation groups. Effect sizes were modeled such that an odds ratio (OR) greater than 1 indicated higher odds of the event occurring in the surgery group than in the ablation group.

Pooled ORs with 95% confidence intervals (CIs) were estimated using a random-effects model on the log-OR scale, with the between-study variance (τ²) estimated by restricted maximum likelihood. Random-effects CIs were calculated using the Hartung-Knapp adjustment. For studies with zero-event cells, a continuity correction of 0.5 was applied only to the affected studies. Studies with missing event data or total counts for a given outcome were excluded from the corresponding analysis.

Statistical heterogeneity was assessed for each outcome using τ², the I² statistic, and Cochran’s Q test and was reported for all pooled estimates. Forest plots were generated for each outcome. Small-study effects were assessed visually using funnel plots, and funnel plot asymmetry was evaluated formally using Peters’ regression test for outcomes that included at least 10 studies. All statistical analyses were performed using R version 4.6.0 and RStudio 2026.05.0 Build 218 with the meta package (version 8.5-0). Statistical significance was defined as a two-sided p value < 0.05.

RESULTS

The baseline characteristics of the included studies are summarized in Table 1. The analyzed T1N0M0 population included both cT1aN0M0 and cT1bN0M0 cases. Because the primary comparative studies did not consistently report tumor volume, VRR, complete ablation rate, or imaging enhancement criteria, the quantitative meta-analysis focused on consistently reported dichotomous outcomes, including overall complications, tumor progression, recurrence, lymph node metastasis, hoarseness, permanent hoarseness, transient hypoparathyroidism, and permanent hypoparathyroidism (Table 2, Figure 2, Supplementary Figures 1-12).

TABLE 2. Consensus-Aligned Summary of Pooled Meta-Analysis Results Comparing Surgery with Image-Guided Thyroid Ablation.

Outcome	Studies (k)	Pooled OR (95% CI)	I2 (%)	p value
Complication	17	2.75 (1.79-4.22)	40.4	0.043
Progression	14	0.81 (0.57-1.15)	0.0	0.636
Recurrence	16	0.64 (0.42-0.97)	0.0	0.791
LNM	16	0.99 (0.70-1.41)	0.0	0.990
Hoarseness	17	1.20 (0.76-1.90)	17.0	0.255
Permanent hoarseness	17	2.24 (1.23-4.09)	0.0	0.974
Transient hypo-PTH	17	5.67 (2.19-14.67)	21.8	0.200
Permanent hypo-PTH	17	1.35 (0.88-2.07)	0.0	1.000

OR, odds ratio; CI, confidence interval; LNM, lymph node metastasis; hypo-PTH, hypoparathyroidism.

Figure 2.

Summary forest plot of pooled clinical outcomes comparing surgery with image-guided thyroid ablation. The dashed red line indicates an odds ratio of 1 (no difference between groups). OR values greater than 1 indicate higher odds in the surgery group.

LNM, lymph node metastasis.

Meta-analysis of clinical outcomes

Overall complications were assessed in 17 studies. The odds of overall complications were significantly higher after surgery than after IGTA (OR = 2.75, 95% CI 1.79-4.22), with moderate heterogeneity (I² = 40.4%, τ² = 0.171, Cochran’s Q p = 0.043).

Tumor progression was evaluated in 14 studies and did not differ significantly between the surgery and IGTA groups (OR = 0.81, 95% CI 0.57-1.15; I² = 0.0%, τ² = 0, Cochran’s Q p = 0.636). Recurrence, reported in 16 studies, was significantly less likely after surgery than after IGTA (OR = 0.64, 95% CI 0.42-0.97; I² = 0.0%, τ² = 0.061, Cochran’s Q p = 0.791). Likewise, lymph node metastasis, assessed in 16 studies, did not differ significantly between the two groups (OR = 0.99, 95% CI 0.70-1.41; I² = 0.0%, τ² = 0, Cochran’s Q p = 0.990).

Regarding procedure-related morbidity, the incidence of overall hoarseness (17 studies) did not differ significantly between the surgery and IGTA groups (OR = 1.20, 95% CI 0.76-1.90; I² = 17.0%, τ² = 0.241, Cochran’s Q p = 0.255) (Supplementary Figures 1 and 2). In contrast, permanent hoarseness was significantly more frequent after surgery (OR = 2.24, 95% CI 1.23-4.09; I² = 0.0%, τ² = 0, Cochran’s Q p = 0.974). Transient hypoparathyroidism was also significantly more common following surgery than IGTA (OR = 5.67, 95% CI 2.19-14.67; I² = 21.8%, τ² = 0.925, Cochran’s Q p = 0.200). Permanent hypoparathyroidism did not differ significantly between the two treatment modalities (OR = 1.35, 95% CI 0.88-2.07; I² = 0.0%, τ² = 0, Cochran’s Q p > 0.99).

Peters’ regression test revealed no significant funnel plot asymmetry for seven of the eight outcomes (all p > 0.05). Significant asymmetry was detected only for transient hypoparathyroidism (p = 0.002), suggesting that this finding should be interpreted with caution because the extent of surgery, biochemical definitions, and reporting thresholds may have varied across the included studies.

DISCUSSION

This consensus-aligned meta-analysis indicates that IGTA and surgery should be regarded as clinically distinct treatment strategies with different risk-benefit profiles rather than as interchangeable therapeutic options. Surgery was associated with lower odds of recurrence, whereas IGTA was associated with substantially lower procedure-related morbidity, including fewer overall complications, lower rates of permanent hoarseness, and lower rates of transient hypoparathyroidism. The principal clinical implication is therefore a trade-off between maximizing recurrence reduction and preserving voice, parathyroid function, cosmesis, and thyroid tissue.^{9, 14, 15, 48}

This trade-off is particularly relevant in patients with low-risk T1N0M0 PTC, for whom disease-specific survival is excellent and overtreatment remains a recognized concern.^{1, 2, 3, 4, 5,7} For patients at high surgical risk, those with a strong preference for organ preservation, substantial anxiety regarding active surveillance, or a high priority to avoid voice or parathyroid morbidity, IGTA may represent an appropriate treatment option following multidisciplinary evaluation. Conversely, patients who prioritize minimizing recurrence risk or who have unfavorable tumor location, suspected extrathyroidal extension, multifocal high-risk disease, or clinically suspicious lymph nodes are likely to benefit more from conventional surgical management.^{4, 5, 8, 9, 14}

The distinction between tumor progression and recurrence is a key consideration when interpreting these findings. Across the included studies, progression generally referred to persistent or locally progressive disease within or adjacent to the ablation zone, whereas recurrence referred to the development of new malignant foci after initially successful treatment. These inconsistent definitions may explain why tumor progression and lymph node metastasis did not differ significantly between the two groups, whereas recurrence favored surgery. Future studies should distinguish residual disease, local tumor progression, new intrathyroidal recurrence, and nodal recurrence in accordance with the IGTA consensus framework.⁴⁸

Heterogeneity should not be interpreted solely on the basis of I² values. Although most pooled outcomes demonstrated low statistical heterogeneity, clinical heterogeneity remains important because the included studies differed in study design, ablation modality, operator experience, tumor size distribution, extent of surgery, use of prophylactic central neck dissection, biochemical definitions of hypoparathyroidism, and duration of follow-up. The significant result of Peters’ regression test for transient hypoparathyroidism likely reflects this variability in surgical practice and outcome ascertainment rather than a single, uniform treatment effect.^{9, 14, 21, 22}

Nevertheless, technical standardization remains essential for the appropriate interpretation of IGTA outcomes. Real-time high-frequency ultrasound guidance, trans-isthmic needle or electrode placement, the moving-shot technique, careful hydrodissection with 5% dextrose, and continuous voice monitoring are not merely technical considerations but key determinants of ablation completeness and complication prevention.^{14, 21, 22, 48}

Existing long-term and multicenter studies support excellent local tumor control with IGTA in carefully selected patients with low-risk PTMC, with reported complete disappearance or local control rates exceeding 95% in selected cohorts.^{14, 23, 27, 28, 30, 31} However, most comparative evidence is observational, and patient selection may favor IGTA in smaller, less invasive, or more favorably located tumors. Therefore, the present findings should be interpreted as supporting the carefully selected use of IGTA rather than as evidence that IGTA is oncologically equivalent to surgery for all patients with T1N0M0 PTC.^{15, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47}

Evidence regarding recurrent DTC should be considered separately from that for primary T1N0M0 PTC. In previously operated necks, repeat surgery carries an increased risk of recurrent laryngeal nerve and parathyroid injury, whereas IGTA can provide effective local control for selected nodal or soft-tissue recurrences with low cumulative morbidity.^{10, 11, 12, 13,22,24,25} However, these data should not be conceptually combined with those for primary low-risk PTC because patient anatomy, prior treatment history, the interpretability of serum thyroglobulin levels, and therapeutic objectives differ substantially.

Preprocedural evaluation should therefore be viewed as a patient selection and safety assessment rather than merely a procedural checklist. High-resolution ultrasound should document tumor size, location, relationship to the thyroid capsule, proximity to the danger triangle, multifocality, and nodal status. Cross-sectional imaging may be required when ultrasonography provides insufficient information. Cytologic or histologic confirmation, patient counseling, voice assessment, and endocrinology consultation are essential components of a standardized IGTA care pathway.^{14, 21, 22, 48}

Biomarker monitoring also requires a more nuanced interpretation. Serum thyroglobulin (Tg) and anti-thyroglobulin antibodies (TgAb) are useful adjunctive markers after total thyroidectomy or in recurrent DTC because changes in their levels may reflect residual or recurrent disease burden.^{4, 5, 22} In contrast, following IGTA for primary PTC, when a substantial amount of normal thyroid tissue is preserved, serum Tg is not a reliable standalone marker of early treatment efficacy and may remain difficult to interpret for several months. Accordingly, Tg and TgAb should not be used as primary early efficacy endpoints in this setting. When measured, they should generally be assessed no earlier than 6 months after ablation and interpreted by clinicians with endocrinology expertise in conjunction with high-resolution ultrasound and, when indicated, cross-sectional imaging.^{4, 5, 22, 48}

Current guidelines and consensus statements support the use of ultrasound-guided IGTA for selected malignant thyroid conditions, particularly low-risk PTMC and locoregional recurrent DTC in patients who decline surgery, are poor surgical candidates, or require a minimally invasive local treatment option.^{14, 21, 22, 48} These recommendations do not advocate the indiscriminate replacement of surgery; rather, they support the multidisciplinary, risk-adapted use of IGTA with standardized reporting and follow-up (Table 3, Figure 3).

TABLE 3. Guideline and Consensus Positions on Image-Guided Thyroid Ablation for Malignant Thyroid Disease.

Guideline/organization	Year	Target condition(s)	Key recommendations
Korean Society of Thyroid Radiology21,22	2017/2025	Recurrent DTC, PTMC	Supports RFA as an alternative to surgery for recurrent DTC and low-risk PTMC in high surgical risk/refusal patients.
ETA/CIRSE14	2021	Low-risk PTMC, recurrent DTC	Supports RFA in selected malignant cases when surgery is contraindicated or declined.
The 2022 Multidisciplinary Consensus50	2022	Malignant thyroid disease	Supports use of US-guided ablation technologies for select malignant thyroid conditions.
American Association of Clinical Endocrinology (AACE) Disease State Clinical Review51	2022	Small primary thyroid cancer, Locoregional recurrence (DTC)	Supports image-guided ablation for non-surgical candidates.

DTC, differentiated thyroid carcinoma; PTMC, papillary thyroid microcarcinoma; RFA, radiofrequency ablation; ETA, European Thyroid Association; CIRSE, Cardiovascular and Interventional Radiological Society of Europe; US, ultrasound; ATA, American Thyroid Association.

Figure 3.

Schematic illustration of the trans-isthmic approach and moving-shot technique used during image-guided thyroid ablation. The shaded area represents the danger triangle, corresponding to the expected anatomical course of the recurrent laryngeal nerve. The vagus nerve appears as a round hypoechoic structure located between the internal jugular vein and the common carotid artery.

V, vagus nerve; E, esophagus; T, trachea; RLN, recurrent laryngeal nerve; D, danger triangle.

Future perspectives

Future research should address the unresolved comparative questions identified in the present analysis. These include the long-term non-inferiority of IGTA with respect to recurrence-free survival, the effects of tumor size and location on ablation completeness, optimal follow-up intervals, patient-reported outcomes, cost-effectiveness, and the standardized reporting of complications. Prospective multicenter studies, randomized controlled trials where feasible, and international registries developed in accordance with the IGTA consensus framework will be essential to determine which patients are most likely to benefit from IGTA and which should continue to undergo surgical treatment.⁴⁸

IGTA is a minimally invasive, organ-sparing treatment option for carefully selected patients with T1N0M0 PTC. In this meta-analysis, surgery was associated with lower odds of recurrence, whereas IGTA was associated with fewer procedure-related complications, particularly permanent hoarseness and transient hypoparathyroidism. These findings support individualized, multidisciplinary decision-making rather than a universal preference for either treatment approach. Long-term prospective comparative studies using standardized IGTA terminology, efficacy endpoints, and complication reporting are needed before durable oncologic equivalence with surgery can be established.

Supplementary Materials

Supplementary Figures

https://balkanmedicaljournal.org/img/files/2026.2026-3-104-supplee-1.pdf