Abstract
Introduction
The management of residual or new ground-glass nodule (GGN)-like lung cancer after video-assisted thoracoscopic surgery (VATS) is challenging for patients who are not suitable for reoperation. This retrospective, large-sample, multicenter study aimed to evaluate the feasibility, safety, and preliminary efficacy of microwave ablation (MWA) for residual GGN-like lung cancer after VATS in early-stage lung cancer.
Methods
A total of 216 patients with 216 residual GGN-like lung cancers who underwent 235 procedures of CT-guided percutaneous MWA after VATS (R0) of stage I-IIA lung adenocarcinoma from July 2016 to December 2023 were included in the study. The primary endpoints were technical success, complications, and pulmonary function test (PFT) variations after the MWA procedure. The secondary endpoints were local progression-free survival (LPFS) and overall survival (OS).
Results
The rate of technical success was 100%. The major complications after MWA included pneumothorax (12.3%, 29/235), pleural effusion (5.5%, 13/235), pulmonary infection (2.6%, 6/235), hydropneumothorax (1.3%, 3/235), intrathoracic hemorrhage (0.4%, 1/235), and bronchopleural fistula (0.4%, 1/235). No MWA procedure-related death was observed. The PFT at 1–3 months after MWA was not significantly different from the baseline. The median follow-up duration was 58.5 months, and the 1-, 3- and 5-year OS rates were 100%, 99.1% and 96.3%, respectively. The median follow-up period after MWA was 33.8 months, and the 1-, 2- and 3-year LPFS rates were 100%, 97.7% and 96.3%, respectively.
Conclusions
CT-guided percutaneous MWA is a safe, effective, and potentially curative approach for patients with residual GGN-like lung cancer after VATS.
Supplementary Information
The online version contains supplementary material available at 10.1007/s11547-025-02112-w.
Keywords: Lung cancer, Video-assisted thoracoscopic surgery, Microwave ablation, Ground-glass nodule
Introduction
Lung cancer is the most common cause of cancer-related mortality worldwide [1] and surgery remains the gold standard treatment for patients with early-stage lung adenocarcinoma. Video-assisted thoracoscopic surgery (VATS) for lung resections has been introduced as a minimally invasive approach compared to traditional open thoracotomy and is the preferred surgical modality for resectable early-stage lung cancer [2]. However, residual pulmonary ground-glass nodules (GGNs) may increase in size or have solid components during the follow-up period after VATS (the generally considered early manifestations of lung cancer) [3]. Although VATS can be performed again to remove the residual GGN-like lung cancers, numerous insurmountable obstacles continue to exist. For example, patients with poor cardiopulmonary function cannot tolerate reoperation, or reoperation may further reduce pulmonary function and even increase the incidence of serious complications and mortality [4]. Therefore, many novel local treatment approaches, including image-guided thermal ablation (IGTA) therapy, have been developed. IGTA, as an alternative treatment for inoperable or refused re-operable early-stage lung cancer patients, includes radiofrequency ablation, microwave ablation (MWA), cryoablation, and laser ablation [5–7]. MWA has several potential advantages in treating lung tumors due to its higher convection, lower heat sink effect, higher temperatures, larger ablative zones, and shorter ablative time [8]. MWA has been proven effective for treating GGN-like lung cancer [9, 10]. To the best of our knowledge, there is a lack of published studies addressing the issues related to MWA in GGN-like lung cancer after VATS for early-stage lung adenocarcinoma. Therefore, this retrospective, multicenter study was conducted to analyze the efficacy and safety of computed tomography (CT)-guided MWA for GGN-like lung cancer after VATS for early-stage lung adenocarcinoma.
Material and methods
Patient cohort
Five hospitals participated in this retrospective multicenter study. The treatment strategies for all patients were developed by a multidisciplinary team (MDT) from the departments of thoracic surgery, radiology, pulmonology, medical oncology, radiation oncology, and interventional oncology. The inclusion criteria were as follows: (1) residual GGNs pathologically confirmed as lung cancer after VATS (R0) for stage I-IIA lung adenocarcinoma; (2) pure or mixed GGN with a solid component ratio of ≤ 50%, a largest dimension of 8–30 mm, and located in the peripheral lung; (3) age, 18–80 years; and (4) Eastern Cooperative Oncology Group Performance Status, 0–2. The exclusion criteria were as follows: (1) pulmonary solid nodules; (2) pathologically verified lung metastasis; (3) presence of regional lymph node or distant metastases before initial MWA; (4) chemotherapy or targeted therapy after MWA; (5) presence of other types of malignant tumors; and (6) a follow-up duration of less than 6 months after the MWA procedure.
From July 2016 to December 2023, 8859 consecutive patients underwent CT-guided percutaneous MWA at the five hospitals; 216 patients with 216 residual GGN-like lung cancers underwent a total of 235 percutaneous CT-guided MWA sessions, including 19 repeated sessions for 11 lesions with incomplete ablation and 8 lesions with local progression. The patient selection procedure is shown in Fig. 1.
Fig. 1.
Flowchart of the patient selection criteria
The GGN was defined by a thin-slice CT scan (thickness, 1 mm), with reference to the Fleischner Society and the British Thoracic Society guidelines [11, 12]. GGNs are divided into pure (pGGN) and mixed (mGGN) types. The diameter of the tumor (T) was defined as the largest dimension of the lesion on the lung window setting. Additionally, the largest dimension of consolidation (C) on the lung window setting was measured. The consolidation tumor ratio was defined as the ratio of the largest consolidation dimension in the nodule transverse section to the largest nodule dimension in the lung window image [13, 14].
MWA procedure
MWA of the GGN lesions was conducted under percutaneous CT guidance (LightSpeed 64 VCT, GE Healthcare, Chicago, IL, USA or uCT 760, United Imaging Healthcare Co., Ltd, Shanghai, China or Siemens SOMATOM Sensation 64 CT scanner, Siemens, Germany or NeuViz 16 Platinum, Neusoft, China). The MTC-3C (Vison-China Medical Devices R&D Center, CFDA Certificated No.: 20153251978), ECO-100A1 (ECO Medical Instrument Co., Ltd. CFDA Certificated No.: 20173251268), or KY-2450B (CANYOU Medical Inc., CFDA Certificated No.: 20153251727) microwave ablation system was applied for the procedure. Details of the procedures have been published in our previous reports [15–18]. A second MWA can be performed for incomplete ablation or progression of the local ablation zone.
Pulmonary function tests
Pulmonary function tests (PFTs) were performed before (baseline) and 1–3 months after MWA. The vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1%, maximum mid-expiratory flow (MMEF), and diffusion capacity of the lung for carbon monoxide (DLCO) at 1–3 months after MWA were compared with those at baseline. PFT was performed in patients with major complications (such as pneumothorax or pleural effusion requiring catheter drainage) 1 month after recovering from them.
Follow-up imaging
All patients received a noncontrast chest CT scan 24–48 h after the procedure to detect the presence of related complications. The first chest contrast-enhanced CT was conducted one month after the operation, followed by another scan three months later to assess any complications and confirm complete ablation of the local lesions. Thereafter, the chest CT was performed every 6 months to monitor the progression of the local ablation zone, formation of scars, and development of new lesions in the lung. An annual chest CT was performed after 2 years.
Local response and clinical outcomes
The response was determined based on a focal baseline 4–6 weeks after the procedure and was divided into three categories: complete ablation, incomplete ablation, and local progression [3, 8]. A complete ablation rates indicated the proportion of lesions with complete ablation at some point in time. Local progression-free survival (LPFS) was defined as the time between the initial ablation and the first radiological evidence of local progression in the ablation zone. The 1.3–5-year overall survival (OS) was defined as the time between the initial VATS and death from any cause. The cancer-specific survival (CSS) was defined as the time between the initial VATS and the 5-year death from lung cancer. The 1-, 2-, and 3-year LPFS, OS, and CSS rates were assessed in this study.
Complications assessment
Treatment-related complications were defined as symptoms that occurred within 30 days of the procedure and were evaluated according to the Society of Interventional Radiology criteria, which divides them into major and minor complications, with grades ranging from A to F [19].
Statistical analysis
The SPSS 24.0 software (SPSS Inc., Chicago, IL) was used for statistical analyses. Numerical variables were described as means ± standard deviations or medians with the interquartile ranges, while categorical variables were described as percentages. The K-S test was used to assess the normality of the data, and the t-paired test was used for PFT pre- and post-MWA comparisons. The Kaplan–Meier log-rank test was used for survival curve comparisons. A two-sided p < 0.05 was considered statistically significant.
Results
Patients and nodule characteristics
A total of 216 patients (78 males and 138 females; mean age, 62.2 ± 10.3 years) with 216 GGN lesions (mean largest dimension, 13.2 ± 4.8 mm) underwent 235 percutaneous CT-guided MWA sessions, including 19 repeated sessions for 11 lesions with incomplete ablation and 8 with local progression in the ablation zone. The tumor staging after VATS was as follows: stage IA (202, 93.5%), stage IB (6, 2.8%), and stage IIA (8, 3.7%). All 216 GGN lesions were histologically confirmed as adenocarcinomas by biopsy under CT guidance, including adenocarcinoma in situ, minimally invasive adenocarcinoma, and invasive adenocarcinoma (IAC). The baseline characteristics are summarized in Tables 1 and 2.
Table 1.
Baseline characteristics of 216 lung adenocarcinoma patients after VATS combined with GGN-like lung cancer
| Characteristics | Numbers (%) |
|---|---|
| Age (year), mean ± SD | 62.2 ± 10.3 |
| Sex | |
| Male | 78 (36.1) |
| Female | 138 (63.9) |
| Smoking history | |
| Yes | 36 (16.7) |
| No | 180 (83.3) |
| Multiple GGNs | |
| Yes | 139 (64.4) |
| No | 77 (35.6) |
| VATS resection | |
| Lobectomy | 87 (40.3) |
| Segmentectomy | 34 (15.7) |
| Wedge resection | 69 (31.9) |
| Combine* | 26 (12.0) |
| Stage at VATS resection | |
| IA | 202 (93.5) |
| IA1 | 57 (26.4) |
| IA2 | 115 (53.2) |
| IA3 | 30 (13.9) |
| IB | 6 (2.8) |
| IIA | 8 (3.7) |
| Adjuvant treatment after VATS | |
| Yes | 29 (13.4) |
| No | 187 (86.6) |
VATS video-assisted thoracoscopic surgery, GGN ground glass nodules, SD standard deviation,
Combine*: lobectomy combines segmentectomy, lobectomy combines wedge resection or segmentectomy combines segmentectomy
Table 2.
Baseline characteristics of 216 GGN-like lung cancers
| Characteristics | Numbers (%) |
|---|---|
| Nodule size (mm), mean ± SD | 13.2 ± 4.8 |
| Nodule size | |
| ≥ 8, ≤ 10 mm | 42 (19.4) |
| > 10, ≤ 20 mm | 159 (73.6) |
| > 20, ≤ 30 mm | 15 (6.9) |
| Nodule density | |
| Pure GGN | 78 (36.1) |
| Mixed GGN | 138 (63.9) |
| Location of GGNs | |
| Left upper lobe | 69 (31.9) |
| Left down lobe | 47 (21.8) |
| Right upper lobe | 62 (28.7) |
| Right middle lobe | 10 (4.6) |
| Right down lobe | 28 (13.0) |
| GGNs location vs VATS location | |
| Ipsilateral thorax | 66 (30.6) |
| Same lobe | 30 (13.9) |
| Different lobe | 36 (16.7) |
| Contralateral thorax | 150 (69.4) |
| Patterns of GGNs change | |
| Residual nodules | 184 (85.2) |
| No growth | 30 (13.9) |
| Growth | 154 (71.3) |
| New nodules | 32 (14.8) |
| Histology at MWA, n (%) | |
| AIS | 17 (7.9) |
| MIA | 133 (61.6) |
| IAC | 66 (30.6) |
| Follow-up after VATS (month), M (P25, P75) | 58.5 (46.8, 73.4) |
| Follow-up after MWA (month), M (P25, P75) | 33.8 (27.8, 41.5) |
GGN ground glass nodules, SD standard deviation, VATS video-assisted thoracoscopic surgery, MWA microwave ablation, AIS Adenocarcinoma in situ, MIA minimally invasive adenocarcinoma, IAC invasive adenocarcinoma, M median, P25 percent 25, P75 percent 75
Technical success rate
All patients tolerated the MWA sessions well, and the procedures were completed using planned protocols. Ablative zones covered 216 lesions entirely 24–48 h after the initial procedure. A technical success rate of 100% was achieved in the 235 sessions.
PFT
Of the 216 patients with GGN-like lung cancer, 136 presented with complete PFT results at baseline and 1–3 months after MWA. The PFT variations after the MWA procedure in the 136 patients are shown in Table 3.
Table 3.
The PFT variation of 136 patients after MWA procedure
| Characteristics | pre-MWA | post-MWA | t | p |
|---|---|---|---|---|
| VC | 3.21 ± 0.72 | 3.27 ± 0.75 | −1.335 | 0.184 |
| FVC | 3.23 ± 0.77 | 3.29 ± 0.76 | −1.306 | 0.194 |
| FEV1 | 2.32 ± 0.77 | 2.47 ± 0.71 | −1.304 | 0.173 |
| FEV1% | 90.15 ± 22.14 | 89.04 ± 22.72 | 1.899 | 0.060 |
| MMEF | 1.77 ± 0.83 | 1.72 ± 0.91 | 0.082 | 0.935 |
| DLCO | 6.34 ± 1.70 | 6.26 ± 1.67 | 1.127 | 0.262 |
MWA microwave ablation, VC vital capacity, FVC forced vital capacity, FEV1 forced expiratory volume in 1 s, MMEF maximum mid-expiratory flow, DLCO diffusion capacity of the lung for carbon monoxide
Local response
From July 2016 to September 2024, no patient was lost to follow-up. Three to six months after the initial MWA, 205 out of the 216 lesions were completely ablated, while 11 were incompletely ablated (Fig. 2 and 3, Figure S1 and S2); thus, the primary complete ablation rate was 94.9%. A second MWA was performed on the 11 incomplete ablative lesions, resulting in a 100% complete ablation rate. The mean largest dimension of the 205 complete ablated lesions (12.7 ± 4.2 mm) was significantly (p < 0.001) lower than that of the 11 incomplete ablated lesions (22.3 ± 5.9 mm).
Fig. 2.
A 59-year-old male, lung adenocarcinoma patient of left lung inferior lobe after VATS (pT1bN0M0) with a residual GGN-like lung cancer in the right upper lobe underwent MWA. (A) A mixed GGN located in the left lung inferior lobe with a diameter of 22 mm. (B) The left lung inferior lobe tissues after VATS and the diameter of GGN was 23 mm × 22 mm. (C) The mixed GGN pathologically confirmed as invasive adenocarcinoma (hematoxylin–eosin; × 40). (D) A synchronous pure GGN located in the right upper lobe with a diameter of 3 mm. (E–F) The pure GGN increased from 5 to 12 mm after VATS at 2 and 3 years, respectively. (G) The pure GGN underwent CT-guided percutaneous MWA synchronous puncture biopsy (long arrows: biopsy needle; short arrows: ablative antenna). (H) Immediately post-ablation showing a GGN that was completely covered by ground-gross opacity. (I) Lesion of the right lung upper lobe confirmed as mini-invasive adenocarcinoma (hematoxylin–eosin; × 40). (J) At 72h post the procedure, the lesion was covered by ground-gross opacity, showing a "fried egg" sign. (K–O) Gradually lesion involuting fibrosis was observed at 1, 12,24,36 and 48 months post the procedure, respectively
Fig. 3.
A 67-year-old male, lung adenocarcinoma patient of left lung upper lobe after VATS (pT1aN0M0, MIA) with a residual GGN-like lung cancer in the right lower lobe underwent MWA. (A-B) A mixed GGN with a diameter of 10 mm located in the left upper lobe of lung synchronous with a pure GGN of 15 mm located in the lower lobe of the right lung. (C) The mGGN of the left lung upper lobe underwent lobectomy by VATS (absence of left upper lobe after VATS), pathologically confirmed as invasive adenocarcinoma without hilar and mediastinal lymph node metastasis. (D) The pGGN increased to 20 mm at 3 years after VATS. (E) The pGGN underwent CT-guided percutaneous puncture biopsy, pathologically confirmed as mini-invasive adenocarcinoma. (F) A microwave antenna punctured into lesion. (G-H) The lesion was covered by ground gross opacity immediately after the procedure and 1 month after the procedure. (I-K) Gradually lesion involuting fibrosis was observed at 9, 24 and 36 months post the procedure, respectively. (L) The lesion almost disappeared at 60 months post the procedure
Eight patients with eight ablation zones (3.7%; 8/216) had local tumor progression 13–36 months (Fig. 4) after the initial MWA. No local progression was observed until September, 2024, following the second MWA. The mean largest dimension of the eight locally progressive ablation zones was 20.8 ± 8.1 mm, and that of the 208 completely ablated zones was 12.9 ± 4.4 mm. The mean largest dimension of the 208 lesions significantly differed from that of five local progressive ablation zones (p = 0.003). The other three locally progressive ablation zones were close to large vessels with a mean largest dimension of 21.2 ± 2.1 mm.
Fig. 4.
A 70-year-old male, lung adenocarcinoma patient of left lung upper lobe after VATS (pT1bN0M0, MIA) with a new GGN-like lung cancer in the left inferior lobe underwent MWA. (A-B) Four years ago, a mGGN (26 mm) of left upper lobe of the lung underwent lobectomy by VATS. A new mGGN appeared in the left inferior lobe in follow-up and gradually increased to 23 mm. (C) A microwave antenna punctured into lesion and synchronous biopsy. Pathology: MIA. (D-E) Immediately after the procedure, pneumothorax developed and drainage with a tube. (F) 3 months after the procedure. (G-H) 12 months after the procedure, the ablation zone gradually involuting fibrosis without enhancement. (I) 18 months after MWA, the ablation zone increased. (J-K) 24 months after the MWA, the ablation zone gradually increased to 20 mm with mild enhancement. (L) A second MWA synchronous biopsy conducted (long arrows: microwave antenna; short arrows: biopsy needle; MIA). (M) Immediately after the procedure, a small amount of pneumothorax appeared. (N) 1 month after the second MWA procedure. (O) 6 months after the second MWA procedure
LPFS and OS
During the follow-up period, no mediastinal lymph nodes or distant metastases were observed in the 216 patients. Eight ablation zones in patients presented with local tumor progression at 13, 17, 20, 22, 24, 27, 32, and 36 months after the initial MWA. The 1-, 2- and 3-year-LPFS in the 216 patients were 100% (216/216), 97.7% (211/216) and 96.3% (208/216), respectively. During the follow-up period, eight patients died after the initial MWA, but none of them died due to GGN-like lung cancer; three died of cardiovascular disease at 23, 37, and 46 months, three of cerebral infarction at 26, 38, and 56 months, and two died of chronic bronchitis with respiratory failure at 41 and 54 months. The 1-, 3-, and 5-year OS rates were 100% (216/216), 99.1% (214/216), and 96.3% (208/216), respectively. The 1-, 3- and 5-year CSS rates were 100%, 100%, and 100%, respectively (Fig. 5).
Fig. 5.
Kaplan–Meier survival curves for patients that received MWA treatment for GGN-like lung cancer after VATS. (A) After MWA LPFS for all patients. The estimated LPFS rate was 100% at 1 year, 97.7% at 2 years and 96.3% at 3 years. (B) After MWA OS for all patients. The estimated OS rate was 100% at 1 year, 99.1% at 3 years and 96.3% at 5 years
Side effects and complications
No death related to the MWA procedure occurred during or within 30 days after the procedure.
Side effects
Of the 235 MWA sessions, patients from 25 sessions reported mild to moderate pain, which was relieved after treatment with nonsteroidal drugs. Four patients had mild chest pain or skin sensory disturbance after MWA, lasting from 6 months to 1 year (post-ablation chronic pain syndrome). Furthermore, patients from eight sessions experienced moderate-to-severe cough. The procedure was stopped for those with severe cough (patients from three sessions) and either followed by a subcutaneous midazolam injection or intermitted. A total of 27 patients showed post-ablation syndrome, with the main symptoms being fever (lower than 38.5 °C), fatigue, general malaise, nausea, and vomiting (Table 4).
Table 4.
Complications of post-ablation of 235 sessions
| Complications | Numbers (%) |
|---|---|
| Major complications | |
| Pneumothorax | 29 (12.3) |
| Pleural effusion | 13 (5.5) |
| Intrathoracic hemorrhage | 1 (0.4) |
| Pulmonary infection | 6 (2.6) |
| Hydropneumothorax | 3 (1.3) |
| Bronchopleural fistula | 1 (0.4) |
| Minor complications | |
| Pneumothorax | 45 (19.1) |
| Pleural effusion | 30 (12.8) |
| Intrapulmonary hemorrhage | 29 (12.3) |
| Hydropneumothorax | 3 (1.3) |
| Hemoptysis | 8 (3.4) |
| Cavity | 2 (0.9) |
| Side effects | |
| Pain | 25 (10.6) |
| Cough | 8 (3.4) |
| Post-ablation syndrome | 27 (11.5) |
| Post-ablation chronic pain syndrome | 4 (1.7) |
| Hospital stays (day), M (P25, P75) | 3.0 (2.0, 4.0) |
M median, P25 percent 25, P75 percent 75
Complications
The complications observed in the 235 sessions are listed in Table 4. Pneumothorax was the most common complication (74/235 sessions, 31.5%), of which 29 (12.3%, 29/235) required chest tube drainage. Among the 29 sessions, 3 (1.3%, 3/235) underwent chest tube drainage immediately after MWA procedure, and 26 (11.1%,26/235) received 24 to 48 h after the procedure (Fig. 4). Of the 43 sessions (18.3%, 43/235) of pleural effusion and 6 sessions (2.6%, 6/235) of hydropneumothorax, 13 (5.5%, 13/235) and 3 (1.3%, 3/235) underwent chest tube drainage, respectively. There were 11 sessions of pleural effusion and 2 sessions of hydropneumothorax were performed chest tube drainage within 24 to 48 h after MWA procedure, 2 and 1 were in 48 to 72 h, respectively. Six sessions (2.6%, 6/235) suffered from pulmonary infection mostly within 48 to 72 h after the procedure, which could be effectively controlled by antibiotics based on the results of the sputum (Figure S3). Aspergillus infection was found in one of the six sessions of pulmonary infection, occurring 10 days post-procedure. A small amount of intrapulmonary hemorrhage was observed in 29 sessions (12.3%, 29/235), which required no special treatment. One session (0.4%, 1/235) suffered from massive intrathoracic hemorrhage (hemothorax) after the procedure immediately. A bronchopleural fistula was observed in one session (0.4%, 1/235) during the MWA procedure, but no signs of pericardial effusion or air embolism were observed.
Discussion
The management of residual or new GGN-like lung cancer after VATS is challenging for patients who require reoperation. Although the consensus recommends the use of VATS combined with IGTA for the treatment of multiple lung cancers [7, 20], there is no standard approach for the treatment of residual GGN-like lung cancer after VATS. In this study, we retrospectively evaluated 216 patients with 216 residual GGN-like lung cancers who underwent 235 CT-guided percutaneous MWA after VATS. To the best of our knowledge, this is the first report on MWA in residual GGN-like lung cancer after VATS.
Complications during and after the MWA procedure were often the primary concerns for the ablationalist and the patient. In this study, pneumothorax was the most common complication, with an incidence of 31.5%; however, only 12.3% of the sessions required the insertion of a chest tube. Pleural effusion was the second most common complications, occurring in 18.3% of all sessions, of which only 5.5% required the insertion of a chest tube. Of the six hydropneumothorax sessions (2.6%), three (1.3%) underwent chest tube drainage. In this study, six sessions (2.6%) developed pulmonary infections after the procedure and one was diagnosed with aspergillus infection. All patients were effectively treated with antibiotics based on the sputum results. Pulmonary infection, especially aspergillus infection, is a severe complication that could lead to death if not taken seriously. Huang et al [21]. Reported that the mortality rate of invasive pulmonary aspergillosis secondary to MWA was as high as 26.1%. In the current study, a small amount of intrapulmonary hemoptysis occurred in 22.0% of all sessions and required no special treatment. A massive intrathoracic hemorrhage after ablation is a serious complication that could lead to death. In this study, one patient (0.4%, 1/235) developed a massive intrathoracic hemorrhage after ablation due to damage to the intercostal artery during the puncture. Close monitoring and active medical treatment, such as interventional embolization or thoracotomy, are required in cases of hemothorax. One patient developed a bronchopleural fistula (0.4%) in this study. Bronchopleural fistula is a rare and severe complication after lung ablation. When combined with infection, it can lead to ablation-related death [22]. The management of bronchopleural fistula warrants a multidisciplinary treatment strategy and should be individualized. No pericardial effusion or air embolism was detected in the current study, and the incidence of complications was similar to that reported in previous studies [18, 23]. Only 1.7% of patients developed mild chest pain or chest skin sensory disturbance after MWA, lasting from 6 months to 1 year (post-ablation chronic pain syndrome) [18]. The procedure was completed as per schedule under local anesthesia, alone or combined with sufentanil [24]. It was well tolerated by all the patients, with no mortality during or 30 days after the procedure. Therefore, the technical success rate was 100% in the 235 sessions, indicating that MWA was feasible and safe for the treatment of GGN-like lung cancer after VATS.
VATS has been associated with significantly better postoperative pulmonary function, lesser trauma, shorter chest tube duration, shorter hospital stay, and lesser morbidity compared with open thoracotomy. In addition, VATS produces oncologic outcomes equivalent to those of traditional open thoracotomy [25–27]. Thus, VATS has supplanted open thoracotomy for the treatment of the majority of early-stage lung cancers over the last decade. However, it has certain limitations, such as anesthesia-related accidents, pulmonary function injury (2 months after VATS, the FEV1 loss ranged from 9 to 24%, and after 12 months, it continued to range from 3 to 13%), and postoperative pain [28–30]. Furthermore, an increase in pulmonary function impairment following MWA after VATS was one of the major concerns for the ablationalist and the patient. Li et al [31]. Studied changes in PFTs before (baseline) and one month after CT-guided percutaneous MWA in 133 patients with malignant lung tumors. The changes in PFT included VC, FVC, FEV1, FEV1%, MMEF, and DLCO-SB. The results of their study showed no statistical differences in PFTs between the two time periods (baseline and 1 month after MWA), suggesting that MWA was a lung parenchyma-sparing local treatment and might not affect pulmonary function. In the current study, no significant differences in PFT results were observed between the baseline values and those obtained 1–3 months after MWA. These findings suggested that MWA in residual GGN-like lung cancer after VATS was also a lung parenchyma-sparing local treatment and might not aggravate the damage to pulmonary function.
In 2022, we reported a retrospective comparative study of 204 patients with GGN-like lung cancer who were treated with VATS (n = 103) and MWA (n = 101) [23]. The 3-year OS, LPFS, and CSS rates were 100%, 98.9%, and 100% in the VATS group and 100%, 100%, and 100% in the MWA group, respectively. There were no significant differences in the 3-year LPFS (p = 0.423), OS (p = 1.000), and CSS (p = 1.000) rates between the VATS and MWA groups. In 2023, we reported another retrospective multicenter study to evaluate the outcomes of MWA for 87 patients with GGN-like lung cancer, where the 5-year LPFS, OS, and CSS rates were 96.6%, 84.9%, and 100%, respectively [18]. Similar results were reported by Zhang et al [32] and Chen et al [33]. Although these findings indicated that MWA was effective in treating GGN-like lung cancer or highly suspected malignant GGN, few studies investigated the role of MWA in residual GGN-like lung cancer after VATS. In the current study, the LPFS rates were 97.7% and 96.3% at 2 and 3 years, respectively, the OS rates were 99.1% and 96.3% at 3 and 5 years, respectively, and the CSS rates were 100% and 100% at 3 and 5 years, respectively. These results suggested that MWA effectively improved local control and survival and expanded our knowledge of MWA in GGN-like lung cancer after VATS.
In this study, the local tumor progressive rate in treating GGN-like lung cancer in those who underwent the MWA procedure after VATS (3.7%, 8/216) was similar to those reported previously [18, 32, 33]. Eight patients developed local tumor progression after the initial MWA, which was completely controlled after the second MWA. Eleven patients did not achieve complete ablation after the initial procedure and were treated with a second MWA, resulting in complete ablation. These results showed that the repeatability of MWA is feasible and may be considered as one of the advantages in cases with local progression or incomplete ablation zones. According to our results, the main reason for local progression and incomplete ablation zones may be the large size, irregular shape, or proximity to a large blood vessel [34] In addition, a potentially incomplete ablation may lead to local tumor progression.
This study has some limitations. First, it was a retrospective, single-arm, no-randomized, and controlled study. Second, it was not designed to compare the outcomes of MWA and other approaches such as VATS reoperation, SBRT, or other local ablative technology. Finally, the enrollment of MWA patients from five hospitals raises concerns about an ablationalist bias.
In conclusion, this retrospective, large-sample, multicenter study initially confirms that CT-guided percutaneous MWA is a feasible, safe, effective, and potentially personalized novel therapeutic approach for patients with residual GGN-like lung cancer after VATS. However, a prospective, multicenter, randomized, controlled study is needed to clarify the safety and long-term effectiveness of MWA in these patients.
Supplementary Information
Below is the link to the electronic supplementary material.
Funding
This study has received funding by National Natural Science Foundation of China (81502610, 82072028 and 82403598), Shandong Provincial Natural Science Foundation, China (ZR2021MH143 and ZR202211030097) and China Postdoctoral Science Foundation (2023M742168).
Declarations
Conflict of interest
All authors report nothing to disclose.
Ethical approval
This study received approval from the ethics committee of all hospitals and performed in accordance with the Declaration of Helsinki.
Human or animal rights
Research on human participants.
Informed consent
Written informed consent was obtained from all patients for publication and any accompanying images in this study.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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