Microwave ablation for primary or metastatic cancer in the lung

Lung cancer is one of the most common types of cancer. The symptoms often do not appear until the disease is at an advanced stage, and the prognosis is generally poor. Cancer that begins in the lungs is called primary lung cancer. There are 2 main types of primary lung cancer: small-cell lung cancer (which is fast growing and can spread quickly) and non-small-cell lung cancer (which usually grows and spreads slowly; this includes squamous cell carcinoma, adenocarcinoma and large-cell carcinoma).

Cancer that starts in one part of the body and spreads via the blood stream to the lungs is known as secondary lung cancer (also called metastatic lung cancer or lung metastasis). Common tumours that metastasise to the lungs include breast cancer, colon cancer, prostate cancer, sarcoma, bladder cancer, neuroblastoma and Wilm's tumour.

NICE's guideline on lung cancer describes the treatment of non-small-cell and small-cell lung cancer. The choice of treatment for primary or metastatic cancer in the lung depends on the type, size, position and stage of the cancer, and the patient's overall health. Common treatments for primary or metastatic cancer in the lung include surgery, chemotherapy, radiotherapy, or a combination of these. Other treatments include photodynamic therapy, thermal ablation, immunotherapy and biological therapy.

The procedure is usually done using general anaesthesia, and occasionally using local anaesthesia and sedation. Under imaging guidance, a small probe is advanced through the chest wall and into each targeted lesion. It delivers high-frequency microwave energy to rapidly agitate water molecules in the tissues. This converts energy into heat, which causes tumour necrosis. Patients with larger tumours or multiple lesions may have multiple pulses of energy delivered within a treatment session or have a staged treatment with multiple sessions.

This procedure aims to destroy tumour cells and create localised areas of tissue necrosis with minimal damage to surrounding normal tissues. Microwave ablation is a minimally invasive procedure. It usually lasts 1 to 2 hours with only 5 to 10 minutes of active ablation time.