The standard treatment of stage I nonsmall cell lung cancer is lobectomy with systematic mediastinal lymph node evaluation. Unfortunately, up to 25% of patients with stage I nonsmall cell lung cancer are not candidates for surgery due to severe medical comorbidities (poor cardiopulmonary function). Image-guided thermal ablation is an alternative for those patients, includes radiofrequency ablation, microwave ablation (MWA), cryoablation, and laser ablation. Compared to them, MWA is a relatively new technique with some potential advantages, such as faster heating times, higher intralesional temperatures, larger ablation zones, less procedural pain, relative insensitivity to “heat sinks,” and less sensitivity to tissue types. However, some advantages of MWA mentioned above (such as higher intralesional temperatures, larger ablation zones) also have potential risks and problems, and an innovative and standardized guidance system is needed to avoid and solve these risks and problems. This article combs our team’s clinical experience over the past decade, summarizes a systematic and standardized guidance system, and names it SPACES (Selection, Procedure, Assessment, Complication, Evaluation, Systemic therapy). Both primary and metastatic pulmonary tumors can be efficiently treated with image-guided thermal ablation in selected candidates. The selection and use of ablation techniques should consider the size and location of the target tumor, the risk of complications, and the expertise and skills of the professionals, among which the size of the target tumor (<3 mm) is a major factor determining the success of ablation.

Lung cancer is the second most common cancer in both men and women. Despite smoking cessation efforts and advances in lung cancer detection and treatment, long-term survival remains low. For early-stage primary lung carcinoma, surgical resection offers the best chance of long-term survival; however, only about one-third of patients are surgical candidates. For nonsurgical candidates, minimally invasive percutaneous thermal ablation therapies have become recognized as safe and effective treatment alternatives, including radiofrequency ablation, microwave ablation, and cryoablation. Lung ablation is also an acceptable treatment for limited oligometastatic and oligorecurrent diseases. This article discusses the technologies and techniques available for tumor ablation of thoracic malignancies, as well as new treatments on the horizon.

Objectives: The objective of the study was to retrospectively investigate the safety and efficacy of computerized tomography-guided microwave ablation (MWA) in the treatment of Stage I non-small cell lung cancers (NSCLCs). Material and Methods: This retrospective, single-center study evaluated 21 patients (10 males and 11 females; mean age 73.8 ± 8.2 years) with Stage I peripheral NSCLCs treated with MWA between 2010 and 2020. All patients were surveyed for metastatic disease. Clinical success was defined as absence of FDG avidity on follow-up imaging. Tumor growth within 5 mm of the original ablated territory was defined as local recurrence. Welch t-test and Fisher’s exact test were used for univariate analysis. Hazard ratio (HR) and odds ratio (OR) were determined using Cox regression and Firth logistic regression. Significance was P< 0.05. Data are expressed as mean ± standard deviation. Results: Ablated tumors had longest dimension 17.4 ± 5.4 mm and depth 19.7 ± 15.1 mm from the pleural surface. Median follow-up was 20 months (range, 0.6–56 months). Mean overall survival (OS) following lung cancer diagnosis or MWA was 26.2 ± 15.4 months (range, 5–56 months) and 23.7 ± 15.1 months (range, 3–55 months). OS at 1, 2, and 5 years was 67.6%, 61.8%, and 45.7%, respectively. Progression-free survival (PFS) was 19.1 ± 16.2 months (range, 1–55 months). PFS at 1, 2, and 5 years was 44.5%, 32.9%, and 32.9%, respectively. Technical success was 100%, while clinical success was observed in 95.2% (20/21) of patients. One patient had local residual disease following MWA and was treated with chemotherapy. Local control was 90% with recurrence in two patients following ablation. Six patients (28.6%) experienced post-ablation complications, with pneumothorax being the most common event (23.8% of patients). Female gender was associated with 90% reduction in risk of death (HR 0.1, P = 0.014). Tumor longest dimension was associated with a 10% increase in risk of death (P = 0.197). Several comorbidities were associated with increased hazard. Univariate analysis revealed pre-ablation forced vital capacity trended higher among survivors (84.7 ± 15.2% vs. 73 ± 21.6%, P = 0.093). Adjusted for age and sex, adenocarcinoma, and neuroendocrine histology trended toward improved OS (OR: 0.13, 0.13) and PFS (OR: 0.88, 0.37) compared to squamous cell carcinoma. Conclusion: MWA provides a safe and effective alternative to stereotactic brachytherapy resulting in promising OS and PFS in patients with Stage I peripheral NSCLC. Larger sample sizes are needed to further define the effects of underlying comorbidities and tumor biology.

This retrospective study aimed to evaluate the safety and efficacy of microwave ablation (MWA) for lung malignancies in patients with severe emphysema. The clinical records of 1075 consecutive patients treated for malignant lung tumors in our department were retrospectively reviewed. Emphysema was assessed based on standard-dose computed tomography (CT) and was considered severe when it occupied ≥25% of the lung. Overall, 26 patients (24 men and 2 women; mean age ± standard deviation [SD]: 71.23 ± 8.18 years, range: 59–88 years) with severe emphysema underwent CT–guided percutaneous MWA for treating 26 tumors (24: non-small cell lung cancer and 2: metastases). The mean tumor size was 3.0 cm (SD: 1.5, range: 1.2–6.5 cm). Follow-up was performed with CT at 1, 3, 6, 12 months after ablation, and every 6 months thereafter. Complications and efficacy were evaluated. The median follow-up duration in all patients was 17.5 months (range: 5–37 months, interquartile range: 15.8). The mortality rate was 0% within 30 days after ablation. Major complications including pneumonia, lung abscess and refractory pneumothorax occurred in 19.2% (5/26) patients. The technical success and efficacy rates were 88.5% (23/26) and 87.0% (20/23), respectively, and the local tumor progression rate was 30.0% (6/20). MWA appears to be a safe and effective therapeutic option for treating lung malignancies in patients with severe emphysema.

The aim of the present study was to compare the safety and efficacy of cryoablation (CA) and microwave ablation (MWA) as treatments for non‑small cell lung cancer (NSCLC). Patients with stage IIIB or IV NSCLC treated with CA (n=45) or MWA (n=56) were enrolled in the present study. The primary endpoint was progression‑free survival (PFS); the secondary endpoints included overall survival (OS) time and adverse events (AEs). The median PFS times between the two groups were not significantly different (P=0.36): CA, 10 months [95% confidence interval (CI), 7.5‑12.4] vs. MWA, 11 months (95% CI, 9.5‑12.4). The OS times between the two groups were also not significantly different (P=0.07): CA, 27.5 months (95% CI, 22.8‑31.2 months) vs. MWA, 18 months (95% CI, 12.5‑23.5). For larger tumors (>3 cm), patients treated with MWA had significantly longer median PFS (P=0.04; MWA, 10.5 months vs. CA, 7.0 months) and OS times (P=0.04; MWA, 24.5 months vs. CA, 14.5 months) compared patients treated with CA. However, for smaller tumors (≤3 cm), median PFS (P=0.79; MWA, 11.0 months vs. CA, 13.0 months) and OS times (P=0.39; MWA, 30.0 months vs. CA, 26.5 months) between the two groups did not differ significantly. The incidence rates of AEs were similar in the two groups (P>0.05). The number of applicators, tumor size and length of the lung traversed by applicators were associated with a higher risk of pneumothorax and intra‑pulmonary hemorrhage in the two groups. Treatment with CA resulted in significantly less intraprocedural pain compared with treatment with MWA (P=0.001). Overall, the present study demonstrated that CA and MWA were comparably safe and effective procedures for the treatment of small tumors. However, treatment with MWA was superior compared with CA for the treatment of large tumors.

Objective: This study evaluated the effect of oxytocin administration prior to microwave ablation (MWA) of hypervascular uterine fibroids. Methods: Thirty-two patients with 38 hypervascular uterine fibroids (Adler blood flow grade 3) were equally apportioned to receive intravenous oxytocin infusion (0.32 U/min) 20 min before ultrasound-guided percutaneous MWA, or no oxytocin (control). Changes in Adler blood supply grade and myoma volume were observed via color Doppler ultrasonography (CDU). All patients underwent quantitative ablation with single or double needle and microwave power 50 W (180 s). Treatment continued for those who did not reach the therapeutic goal. The myoma necrotic volume was evaluated by contrast-enhanced ultrasound. Ablation rate was the percent of MRI nonenhanced myoma volume after treatment, relative to myoma volume before treatment, 2 days after surgery. Results: Twenty minutes after oxytocin administration, CDU showed significant decrease of blood vessels in myomas, and Adler blood supply decreased from grade 3 to grade 1 or grade 0 in 10 and 9 myomas, respectively. Myoma volumes were reduced by 2.12 ± 0.24%. Necrotic volumes in the oxytocin (control) groups were 36.96 ± 2.78 cm³ (22.68 ± 3.38 cm³) and ablation rates were 95.4 ± 2.7% (85.7 ± 3.3%; t = 12.68, 8.866, p = 0.001, both). No serious complication was noted. Conclusion: Intravenous oxytocin administered before percutaneous MWA of hypervascular uterine fibroids can effectively block the blood supply vessels of the myoma, reduce the heat sink effect, and thereby increase the ablation volume and improve the local therapeutic effect.