This study investigated whether thermal ablation had an equivalent prognostic impact compared to wedge resection in patients with < 2 cm stage I NSCLC. The analyses revealed that patients who received thermal ablation had a higher risk of poor OS than wedge resection. However, according to the stratified analysis, OS and OSS between thermal ablation and wedge resection appear similar in any histology or grade. Finally, when stratified by tumor size, among patients with tumor size < 1 cm, no difference was found in OS and CSS between the two procedures. However, in patients with tumor size 1 to 2 cm, thermal ablation appears to have a higher risk of poor OS.

When NSCLC is diagnosed at an early stage during chest CT screening, sublobar resection is used as an alternative surgical strategy [19]. Segmentectomy shows better survival than wedge resection for tumors < 2 cm, with no difference for ≤ 1 cm tumors [20]. Sublobar resection matches lobectomy in survival and improves pulmonary function in peripheral stage IA NSCLC ≤ 2 cm [21]. Another study documented that for patients with NSCLC and peripheral tumors ≤ 2 cm, it is contentious whether segmentectomy or wedge resection is preferable [22]. Suzuki et al. find no significant difference in postoperative complications between segmentectomy and lobectomy, except for more air leakage in segmentectomy [23].

Although sublobar resections were developed to limit the functional impairments associated with lobectomy in early NSCLC, approximately 20% of patients are still ineligible for surgical procedures due to relatively severe comorbidities [24]. For instance, many individuals are ineligible for surgery because of advanced age or the presence of comorbidities such as pulmonary insufficiency or atherosclerosis [24]. An important advantage of thermal ablation over surgical resection is that it can destroy lung tumors by locally heating the lung parenchyma, while avoiding damage to surrounding normal lung tissue [25, 26]. Nevertheless, whether thermal ablation has equivalent long-term survival outcomes to wedge resection in early NSCLC is unclear and needs substantive evidence.

Using the SEER data from 2004 to 2019, our analytic results indicate that thermal ablation may be the best option for individuals with stage I NSCLC with a tumor size of 1 cm, since it is less invasive and led to no significantly different OS and CSS compared to wedge resection. As mentioned above, Zeng et al., querying the same database but with a shorter follow-up than our study, assessed the prognostic impact of thermal ablation versus wedge resection for stage I NSCLC with mixed tumor sizes [16]. It should be noted that no analysis was performed according to different tumor sizes in their report. Moreover, the result of their study was likely biased due to the lack of exclusion of chemotherapy and radiotherapy, thus limited interpretations.

The use of thermal ablation as an alternate therapy for patients who are not surgical candidates has increased because only one-third of stage I NSCLC patients are eligible for curative surgical resection [27]. It was previously believed that patients who received thermal ablation alone have a greater risk of local tumor recurrence because of insufficient ablation margins [28]. Inconsistent with our findings, a meta-analysis compared the relative safety and efficacy of thermal ablation and sublobar resection for treating stage I NSCLC and indicated that ablation was associated with shorter survival compared to surgery [29]. With regard to safety, it has been reported that thermal ablation for NSCLC, via percutaneous or bronchoscopic methods, can lead to complications such as pneumothorax, pleural effusion, pneumonia, and, rarely significant hemorrhage. However, bronchoscopic approaches generally show a safer profile with fewer adverse events [30, 31]. RFA shares similar complications, but these are typically temporary and manageable with appropriate treatments [32].

Each technology for thermal ablation has a benefit or detriment [33]. A previous single-center, retrospective study by Huang et al. evaluated 10-year OS, progression-free survival (PFS), and local control rates in patients with inoperable stage IA NSCLC who underwent CT-guided RFA [34]. The results showed that CT-guided RFA performed by a thoracic surgeon is a feasible, safe, and effective procedure for inoperable high-risk early-stage NSCLC, and should be considered as an alternative to sublobar resection. A recent study by Li et al. indicated that RFA, compared to no treatment, has better survival in patients with unresected stage IA NSCLC [35]. Another study by Streitparth et al. also highlighted the feasibility and safety of RFA in early, NSCLC [32].

The study is inherently limited by its retrospective and observational nature. The SEER database lacks data on complications, cardiopulmonary function, performance status, and recurrence, precluding the incorporation of these into the analysis. In addition, SEER does not make it possible to know the ablation energy used, locations of tumors (central or peripheral), or patients’ baseline comorbidities. Furthermore, the notable low number of ablation cases across the entire population, as well as within specific subgroups analyzed, while potentially reflecting real-world scenarios, could pose a challenge to the reliability of the analytic results. Despite the abovementioned limitations, the present analyses utilized the latest data in a national cohort, and are likely to be robust under the implementation of PSM and multiple stratified analyses.