The efficacy and safety of improved laser ablation in the lung: a pilot study

Background: Laser ablation (LA) offers advantages such as shorter ablation time and impedance independent, which has received significant attention for the treatment of lung cancers. However, the small ablation area of LA restricts its clinical application scenarios. This pilot study evaluated the efficacy and safety of LA enhanced by saline injection (0.5–1 mL) via a modified applicator with a waterflood path in patients with early-stage lung adenocarcinoma unfit for surgery.

Methods: The LA-guiding applicator was improved by designing a waterflood path and injecting 0.5–1 mL saline into the target zone in prior to ablation. We performed LA (3 W, 60 seconds) in the lung of three pigs and obtained computed tomography (CT) scans at 30 min, 1 day, 7 days, and 30 days after ablation. Microwave ablation (MWA) (40 W, 240 seconds) was introduced as a control to assess the efficacy of the improved LA. Moreover, six patients with lung adenocarcinomas manifesting as ground glass nodules (GGNs) were enrolled to assess the efficacy and safety of the modified LA.

Results: The improved LA significantly increased the ablation area compared to the pre-modified LA and achieved the similar ablation area to MWA in the pig lungs. Tissues in both the LA and MWA zones exhibited coagulative necrosis, and the extent of necrosis was similar by evaluating the expression of caspase 3 and caspase 9. Six patients with eight GGNs (mean diameter, 12.75 mm; range, 7–22 mm) received improved LA treatment, achieving a 100% complete ablation rate. One patient experienced mild pneumothorax, and no major complications occurred.

Conclusions: The improved LA significantly increases the ablation area with safety, and the long-term clinical outcomes warrant further validation through large-sample clinical trials.

Keywords: Laser ablation (LA); microwave ablation (MWA); lung cancer

 

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Key findings

• The improved laser ablation (LA) significantly increased the ablation area.

• The improved LA was safe and effective in pre-clinical study.

• The improved LA was safe and effective in the treatment of ground glass nodules.

What is known and what is new?

• LA treats small lung tumors (<1.5 cm) precisely but has limited ablation zones.

• This study introduces a saline-enhanced LA system via a novel applicator with a waterflood path. Pre-ablation saline injection (0.5–1 mL) safely expands ablation zones to 2 cm.

What is the implication, and what should change now?

• Implication: saline-enhanced LA overcomes size limitations (≤2 cm), offering a faster (60 seconds), precise alternative to microwave ablation/radiofrequency ablation for high-risk patients.

• Change: (I) adopt this modified LA for tumors 1–2 cm, especially near critical structures. (II) Update guidelines to include saline-enhanced LA as a first-line ablation option.