Microwave Ablation (MWA) is a minimally invasive interventional oncology procedure that uses heat to destroy cancer cells. A thin needle-like probe called an antenna is placed within the tumour and produces microwave energy, causing water molecules in the surrounding tissue to move rapidly and generate heat. This creates a controlled area of tissue destruction around the probe.
MWA is usually performed through the skin under ultrasound, CT or other imaging guidance by an interventional oncologist or interventional radiologist. It may also be performed during laparoscopic or open surgery in selected cases. Despite using the term “microwave,” MWA is not a form of radiation therapy and does not use ionising radiation to destroy the tumour.
MWA is a local treatment generally used for small or limited tumours. It may be considered when surgery is not suitable or when preserving healthy tissue is important. It may be used alone or combined with surgery, systemic therapy, radiation therapy, embolization or other cancer treatments.
- Primary liver cancers, including selected hepatocellular carcinomas
- A limited number of liver metastases
- Selected early-stage lung cancers when surgery is not suitable
- A limited number of lung metastases
- Selected kidney tumours
- Selected adrenal tumours or metastases
- Painful bone tumours or bone metastases
- Small soft-tissue tumours in selected locations
- Residual or recurrent tumours following surgery or other treatment
- Patients who cannot undergo surgery because of other medical conditions or reduced organ function
- Patients for whom surgery would require removal of a significant amount of healthy tissue
- Selected patients requiring local treatment of a limited number of metastatic tumours
- Tumours for which radiofrequency ablation may be less suitable because of their location near blood vessels or the required ablation volume
How Microwave Ablation Is Performed
Before Treatment
The interventional oncologist or interventional radiologist reviews the diagnosis, biopsy findings, imaging, previous treatments and medical history.
CT, MRI, ultrasound, PET-CT or other imaging is used to assess the tumour and plan a safe route for the antenna.
Blood tests are performed to assess blood counts, kidney or liver function and the ability of the blood to clot.
Blood-thinning medicines and certain other medications may need to be temporarily adjusted under medical guidance.
The patient is usually instructed to avoid eating or drinking for a specified period before the procedure.
An anesthesia assessment may be performed when deep sedation or general anesthesia is planned.
Antibiotics may be recommended in selected cases.
The possible need for a biopsy before or during the procedure is discussed.
The treating team determines the number and position of antennas needed to create the planned treatment area.
The expected benefits, possible risks and possibility of requiring further treatment are explained.
During Treatment
The patient is positioned according to the tumour’s location.
Local anesthesia, sedation or general anesthesia is administered depending on the treatment area and procedure.
Ultrasound, CT or another imaging method is used to locate the tumour.
A small skin puncture is made, and one or more microwave antennas are guided into the tumour.
The position of each antenna is confirmed before energy is delivered.
Microwave energy generates heat within the tissue surrounding the antenna.
The tumour and a planned margin around it are treated where this can be done safely.
The temperature, energy delivery and patient’s condition are monitored throughout the procedure.
The antenna may be repositioned, or more than one antenna may be used, to treat different parts of the tumour.
The antenna is removed after the planned ablation is complete, and a dressing is placed over the insertion site.
The procedure may take approximately one to three hours, depending on the number, size and location of the tumours.
After Treatment
The patient is monitored in a recovery area while the effects of sedation or anesthesia wear off.
Pain relief and other medicines are provided when needed.
Follow-up imaging may be performed immediately or shortly after treatment to assess the ablation area and identify complications.
Some patients can return home on the same day, while others may require an overnight hospital stay.
Mild pain, tiredness, low-grade fever, nausea or flu-like symptoms may occur for a few days.
The dressing and insertion site should be cared for according to the team’s instructions.
Strenuous activity may need to be avoided for a short period.
Follow-up CT, MRI, ultrasound or PET-CT is arranged to assess the treated area.
Additional ablation or another treatment may be recommended if viable tumour remains or the cancer returns.
Potential Benefits of Microwave Ablation
- Minimally invasive treatment through a small skin puncture
- Destruction of a localised tumour without removing the entire organ
- Preservation of surrounding healthy tissue where possible
- An alternative for selected patients who cannot undergo surgery
- The ability to generate high temperatures within the tumour
- Creation of a predictable treatment area in many appropriately selected tumours
- The ability to treat some larger tumours or create larger ablation zones using multiple antennas
- Less effect from heat being carried away by blood flow compared with some other thermal ablation techniques
- A relatively short treatment time
- Less pain and a shorter recovery period than major surgery in many cases
- A short hospital stay, with same-day discharge possible for some patients
- The possibility of repeating the treatment if clinically appropriate
- The ability to be combined with surgery, embolization, systemic therapy or radiation therapy as part of a multidisciplinary treatment plan
Side Effects of Microwave Ablation
- Pain, tenderness, bruising or swelling at the insertion site
- Tiredness or weakness
- Low-grade fever, chills or flu-like symptoms after ablation
- Nausea or reduced appetite
- Bleeding or a collection of blood near the treated area
- Infection at the insertion site or within the treated organ
- Injury to nearby nerves, blood vessels or organs
- Skin or tissue burns
- Incomplete tumour destruction or cancer returning at the edge of the treated area
- Collapse of part of the lung or air around the lung following lung ablation
- Bleeding into the chest following treatment of a lung tumour
- Injury to the bile ducts, gallbladder, bowel or diaphragm following liver ablation
- Urine leakage or injury to nearby structures following kidney ablation
- Changes in liver, kidney or other organ function
- Rare blood clots or serious reactions related to anesthesia
