Thermal ablation of lung tumours

Thermal ablation is a minimally invasive procedure used to treat lung tumors by using heat to destroy cancerous cells. There are two main types of thermal ablation techniques commonly used for lung tumors: radiofrequency ablation (RFA) and microwave ablation (MWA). 

Indications

1. Small Lung Tumors: Thermal ablation is typically used for small lung tumors (less than 3-5 cm in diameter) that are localized and not suitable for surgical resection.
2. Primary Lung Cancer: It can be used for early-stage primary lung cancer or as a palliative treatment for advanced-stage lung cancer to alleviate symptoms and improve quality of life.
3. Metastatic Lung Tumors: Thermal ablation may also be considered for metastatic tumors in the lungs originating from other primary cancers.

Pre-procedure Preparation

1. Patient Assessment:
   • Comprehensive evaluation of the patient’s overall health, lung function, tumor characteristics, and medical history.
   • Imaging studies (CT scan, PET scan, MRI) to determine the size, location, and accessibility of the lung tumor.
2. Informed Consent:
   • Explanation of the procedure, its purpose, potential risks, benefits, and alternatives to the patient or their caregivers. Informed consent is obtained.
3. Imaging and Planning:
   • CT or ultrasound imaging is used to precisely localize the lung tumor and plan the optimal needle insertion trajectory for thermal ablation.
4. Medications:
   • Medications may be administered to manage pain, anxiety, or to provide sedation during the procedure, depending on patient preference and medical condition.

Procedure Steps

1. Patient Positioning:
   • The patient is positioned on the CT scanner table or ultrasound bed in a specific position based on the location of the lung tumor.
2. Local Anesthesia:
   • Local anesthesia is administered to numb the skin and underlying tissues at the insertion site(s) where the ablation needles or probes will be inserted.
3. Needle Insertion:

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     Under imaging guidance (CT or ultrasound), the ablation needle or probe is inserted through the skin and advanced into the tumor.
   • For RFA, the needle delivers high-frequency electrical currents to generate heat and destroy the tumor cells.
   • For MWA, the probe emits microwave energy to rapidly heat and ablate the tumor tissue.
4. Monitoring and Control:
   • Real-time imaging (CT or ultrasound) is used during the procedure to monitor the position of the needle/probe and the extent of tumor ablation.
   • Temperature sensors on the probes help control and monitor the ablation process to ensure adequate tumor destruction while minimizing damage to surrounding healthy tissues.
5. Ablation Process:
   • The ablation procedure is performed for a specific duration, typically a few minutes, to achieve complete tumor ablation and destruction.
   • Multiple probes may be used for larger tumors or to ensure thorough coverage of the tumor volume.
6. Post-Ablation Assessment:
   • Post-ablation imaging studies (CT scan or MRI) may be performed immediately or shortly after the procedure to evaluate the extent of tumor ablation and assess for any complications.

Post-procedure Care

1. Monitoring:
   • The patient is monitored closely post-procedure for a few hours to assess vital signs, respiratory status, and any immediate complications such as pneumothorax or pain.
2. Pain Management:
   • Pain or discomfort at the ablation site is managed with appropriate analgesics as needed.
3. Follow-up:
   • Follow-up appointments are scheduled to monitor the patient’s recovery, assess treatment response, and perform imaging studies to evaluate tumor response and recurrence.

Benefits of Thermal Ablation for Lung Tumors

• Minimally Invasive: Ablation is performed through small incisions or needle insertions, resulting in less pain, shorter hospital stays, and faster recovery compared to surgery.
• Local Treatment: Precisely targets and destroys the tumor cells while preserving surrounding healthy lung tissue.
• Suitable for Inoperable Tumors: Provides a treatment option for patients with lung tumors that are not amenable to surgical resection due to location, size, or medical comorbidities.
• Palliative Care: Offers palliative treatment for patients with advanced-stage lung cancer, improving symptoms such as pain, cough, or shortness of breath.

Risks and Considerations

• Pneumothorax: Risk of pneumothorax (lung collapse) due to needle insertion into the lung tissue, which is typically managed with chest tube placement if necessary.
• Bleeding and Infection: Potential risks associated with any invasive procedure, although they are generally low with thermal ablation techniques.
• Incomplete Ablation: In some cases, complete tumor ablation may not be achieved with a single session of thermal ablation, requiring additional treatments or interventions.
• Tumor Recurrence: There is a risk of tumor recurrence or residual disease following thermal ablation, necessitating regular follow-up and surveillance imaging.

Conclusion

Thermal ablation, including radiofrequency ablation (RFA) and microwave ablation (MWA), is a valuable minimally invasive procedure for treating small lung tumors in patients who are not candidates for surgical resection or prefer a less invasive treatment option. It offers precise tumor destruction, minimal impact on healthy lung tissue, and can be used for both primary lung cancer and metastatic lung tumors. Close monitoring, imaging guidance, and multidisciplinary collaboration are essential for optimal outcomes and patient safety during thermal ablation of lung tumors.