Microwave Ablation for Hepatocellular Carcinoma: Benefits, Risks, and Success Rates
Hepatocellular carcinoma (HCC) is one of the most common liver cancers, commonly related to chronic liver conditions such as hepatitis B, hepatitis C, and cirrhosis. With the development of medicine, different treatment methods have been devised, ranging from surgical resection and liver transplantation to minimally invasive techniques such as microwave ablation. Of these, microwave ablation for liver metastasis has been the target for its specificity in treating tumours with minimal invasion of surrounding healthy liver tissue. This blog covers microwave ablation’s benefits, limitations, and success rate for treating hepatocellular carcinoma.
Learning Microwave Ablation for Hepatocellular Carcinoma
Microwave ablation (MWA) is an emerging thermal ablation technology that uses electromagnetic waves to create high-temperature heat, eventually killing cancer tissue. The treatment involves placing a thin probe directly into the tumour under image guidance, ultrasound, or CT-guided microwave ablation. After placement, the probe releases microwaves that lead to the rapid motion of water molecules, creating heat and causing coagulative necrosis of the tumour cells. The cells shrink over time and are phagocytosed by the body.
MWA is particularly suitable for patients who are not candidates for surgical resection or liver transplantation due to underlying conditions or tumour location. MWA can be delivered percutaneously, laparoscopically, or open, providing adaptability depending on the patient’s medical situation. Its lack of invasiveness and great precision render it a progressively popular choice in current oncology.
Advantages of Microwave Ablation of Hepatocellular Carcinoma
1. Minimally Invasive Method
One of the most significant benefits of microwave ablation is that it is minimally invasive. In contrast to conventional surgery, which involves substantial cuts and long recovery times, MWA is conducted with a catheter-like probe inserted through an infinitesimal cut in the skin. This obviates the necessity for open surgery, which means less trauma to the body and fewer chances of complications like infection and bleeding. Moreover, since the procedure does not necessitate large incisions, the patient usually has less post-operative discomfort and can resume their usual activities much earlier.
2. Effective Tumour Destruction
Microwave ablation is very effective in ablating tumours because it can produce much higher temperatures than other thermal ablation methods. The high temperatures, usually above 100°C, provide a more significant and consistent ablation zone, ensuring complete tumour destruction. This is especially useful in treating tumours in hard-to-reach locations of the liver. The fast and extensive heat distribution also reduces the risk of incomplete ablation, a frequent issue with other methods such as radiofrequency ablation (RFA). By ensuring more complete tumour destruction, MWA minimises the risk of cancer recurrence much more.
3. Maintenance of Healthy Liver Tissue
Liver function preservation is an essential consideration in the management of hepatocellular carcinoma, particularly in those with underlying liver diseases like cirrhosis. In contrast to surgical resection, in which part of the liver containing the tumour is removed, MWA specifically targets and kills malignant cells while preserving as much normal tissue as possible. This selectivity is essential in maintaining liver function, especially in those who could already have impaired hepatic reserves. By minimising collateral damage, MWA improves overall liver preservation, enabling patients to tolerate further treatment if necessary.
4. Shorter Recovery Time
Compared to traditional surgical methods, microwave ablation offers a significantly shorter recovery period. Since the procedure is minimally invasive, hospital stays are generally brief, with many patients being discharged within a day or two. Post-procedural pain is typically mild and can be managed with over-the-counter painkillers. Most patients can resume normal activities within a few days, which is particularly beneficial for those with demanding lifestyles or pre-existing health conditions. The reduced recovery time also lowers healthcare costs and minimises the disruption to a patient’s daily routine.
5. Suitable for Repeated Treatments
One significant advantage of MWA is that it can be performed multiple times if necessary. Unlike surgical procedures, which may not always be feasible for recurrent tumours, MWA allows repeat treatments without significant risks. This makes it an ideal option for patients with recurring hepatocellular carcinoma, as new tumours can be treated without the complications associated with multiple surgeries. Additionally, to improve overall patient outcomes, MWA can be effectively combined with other treatments, such as transarterial chemoembolisation (TACE) or systemic therapies.
Risks and Limitations of Microwave Ablation
1. Risk of Local Recurrence
While MWA is highly effective, there remains a risk of local tumour recurrence, especially in larger tumours or those with irregular margins. The heat generated by the ablation process may not always reach the entire tumour, allowing residual cancer cells to persist. This underscores the importance of careful planning and follow-up imaging to ensure complete tumour eradication. Regular monitoring and, if necessary, additional treatment sessions can help manage this risk effectively.
2. Potential Liver Damage
Although MWA is designed to preserve healthy liver tissue, excessive heat application can inadvertently damage nearby liver structures, leading to complications such as bile duct injuries or liver abscesses. In some cases, transient liver dysfunction may occur, requiring medical management. To minimise these risks, precise imaging guidance is used to carefully control the ablation process and ensure accurate targeting of the tumour.
3. Pain and Post-Procedural Discomfort
Some patients experience pain or mild discomfort at the treatment site following the procedure. While this is generally temporary and manageable with pain relief medications, it can be a concern for some individuals. In rare cases, more severe complications such as infection, bleeding, or damage to adjacent organs may occur, necessitating close post-procedural monitoring.
4. Limited Effectiveness for Large Tumours
MWA is most effective for small to medium-sized tumours, typically less than 5 cm in diameter. Larger tumours may not be wholly ablated in a single session, requiring additional treatment rounds or combination therapies. In cases where the tumour is particularly large or deeply embedded within the liver, alternative treatments such as liver transplantation or combination therapies may be more appropriate.
5. Dependence on Operator Skill and Technology
The success of microwave ablation is highly dependent on the expertise of the medical team and the quality of imaging technology used. Procedures like CT-guided microwave ablation are crucial for ensuring precise placement of the ablation probe and optimising treatment outcomes. However, variations in equipment and operator experience can influence the procedure’s effectiveness, highlighting the importance of seeking treatment at well-equipped, specialised centres.
6. Success Rates and Long-Term Outcomes
Clinical studies indicate that microwave ablation achieves complete tumour ablation in approximately 80-90% of cases when treating small tumours (less than 3 cm). Success rates may vary for larger tumours, but when combined with other treatments, MWA significantly improves overall survival rates. Long-term studies show that five-year survival rates for patients undergoing MWA range between 50% and 70%, making it a viable alternative to surgical resection for carefully selected patients.
7. Emerging Applications of Microwave Ablation
Although primarily used for liver cancer, MWA has also shown promise in treating other malignancies and benign tumours. Microwave ablation of osteoid osteoma is a promising procedure that can be used minimally to treat benign bone tumours invasively. With continued research, MWA will play an increasingly important role in interventional oncology, offering new treatments for various conditions.
Conclusion
Microwave ablation is a highly effective and minimally invasive treatment for hepatocellular carcinoma, offering benefits such as precise tumour targeting, liver function preservation, and shorter recovery times. While some risks exist, such as local recurrence and potential liver damage, careful planning and advanced imaging guidance help mitigate these concerns. Microwave ablation for liver metastasis continues to evolve, providing patients with improved treatment options and quality of life. With ongoing technological advancements, MWA is set to become an even more integral part of liver cancer management.
