Neuroendocrine tumours (NETs) can be complex and challenging to treat, particularly when surgery is not an option. For patients with inoperable or metastatic NETs — especially when the liver is the main site of metastatic disease — Liver Directed Therapies such as embolisation and ablation offer valuable alternatives. These minimally invasive procedures can help reduce tumour burden, manage symptoms, and improve quality of life.
This article provides a comprehensive overview of embolisation and ablation techniques, their role in the treatment of NETs, and how they fit within a broader, multidisciplinary approach to care.
Neuroendocrine Cancer Australia (NECA), is dedicated to assisting individuals diagnosed with NETs and their loved ones. NECA offers a wealth of resources, educational programs, and advocacy efforts aimed at deepening the understanding of NETs, improving patient care, and encouraging research advancements. Patients can engage with NECA’s comprehensive support and information by calling the NET nurse line.
Not all NETs can be surgically removed. In some cases, tumours are located in areas that are difficult to reach, involve multiple sites, or would require the removal of too much healthy tissue. In other cases, a patient’s overall health may prevent them from undergoing major surgery.
Embolisation and ablation offer alternatives in these scenarios. By directly targeting the tumour with minimal damage to surrounding tissues, these approaches can slow tumour growth and improve symptoms without the risks of a major operation.
The liver is the most common site for NET metastasis. For many patients, the majority of their tumour burden is concentrated in the liver, even when the primary tumour originated elsewhere in the body.
In cases of liver-dominant disease, embolisation and ablation can be particularly useful. These techniques focus treatment specifically on liver metastases, reducing the size and activity of tumours in the liver while sparing the rest of the body from systemic side effects.
Many NETs are functional tumours, meaning they secrete hormones that can cause symptoms such as flushing, diarrhoea, wheezing, and abdominal pain. Even when not curable, reducing tumour size or slowing its growth can help manage these symptoms.
Locoregional therapies can lower hormone production by destroying or disrupting tumour tissue. For patients with hormone-related symptoms that have not responded to medication alone, embolisation or ablation may provide much-needed relief.
Embolisation involves deliberately blocking blood vessels that supply nutrients to a tumour. Since NETs are often highly vascular, cutting off their blood supply can cause tumour cells to die or shrink. Several forms of embolisation are used in NET treatment, particularly when managing liver metastases.
HAE targets the hepatic artery — the main blood vessel supplying the liver. Tiny particles are injected through a catheter into the artery, blocking blood flow to the tumour while sparing most of the surrounding healthy liver tissue, which is mainly supplied by the portal vein.
This technique can slow tumour growth, reduce symptoms, and improve liver function. It is particularly effective for patients with multiple liver metastases that are not suitable for surgical removal.
TACE builds on the principles of HAE by combining embolisation with chemotherapy. In this procedure, chemotherapy can be administered via microspheres that contain the chemotherapy or by directly injecting the chemotherapy into the blood vessel feeding the tumour, followed by embolic particles to trap the drug inside the tumour, blocking its blood supply.
By concentrating chemotherapy in the tumour and limiting systemic exposure, TACE can enhance the anti-cancer effect while reducing side effects. It’s typically used for patients with stable liver function and limited disease outside the liver.
Also known as selective internal radiation therapy (SIRT), TARE involves injecting tiny radioactive beads (usually yttrium-90) into the hepatic artery. These microspheres lodge in the tumour’s blood vessels and deliver a localised dose of radiation over several days.
TARE is generally well tolerated and can be used even in patients with more advanced liver disease. It’s a valuable option when other forms of embolisation or systemic treatments have not provided sufficient benefit.
Ablation uses energy to destroy tumour tissue directly. It’s often used when there are only a few tumours or when the tumours are located in areas where embolisation isn’t feasible. Like embolisation, ablation is typically delivered through a needle or probe inserted under imaging guidance.
RFA uses high-frequency electrical currents to generate heat and destroy tumour cells. A probe is inserted directly into the tumour, and thermal energy is applied to kill cancerous tissue while sparing nearby structures.
This technique is most effective for small tumours (usually under 3–5 cm) and can be performed under sedation or general anaesthesia. It is frequently used in the liver, but also in the lungs or other organs when appropriate.
MWA uses electromagnetic waves to produce heat and destroy tumour tissue. Compared to RFA, it tends to create larger zones of ablation more quickly, making it suitable for slightly larger tumours or those in more vascular areas.
MWA is increasingly being adopted due to its efficiency and precision. It can be a particularly good option for patients with multiple small tumours that are not amenable to surgery.
Embolisation and ablation offer several benefits for NET patients:
Despite their benefits, these treatments aren’t suitable for everyone. Some tumours may be too large, too numerous, or located in areas that make the procedures unsafe. In patients with poor liver function or extensive disease, the risks may outweigh the benefits.
Possible side effects include post-embolisation syndrome (pain, fever, nausea), liver damage, or complications from the procedure itself, such as bleeding or infection. Careful patient selection and monitoring are essential.
After embolisation or ablation, patients require regular follow-up to assess the effectiveness of the treatment and detect any recurrence or progression. This usually includes:
Additional treatments may be needed, and patients should be closely monitored for delayed side effects or new disease activity.
Embolisation and ablation are not standalone treatments. They are most effective when integrated into a multidisciplinary treatment plan that includes input from oncologists, radiologists, surgeons, endocrinologists, and NET specialists.
These procedures are often used alongside other therapies such as:
Personalised treatment planning is key. Each patient’s NET behaves differently, and the decision to use embolisation or ablation depends on tumour location, burden, symptoms, and overall health. Collaboration between experts helps tailor care to the individual and improve long-term outcomes.
Cancer Research UK – Radiofrequency ablation and microwave ablation for neuroendocrine tumours (NETs).
https://www.cancerresearchuk.org/about-cancer/neuroendocrine-tumours-nets/treatment/radiofrequency-ablation-microwave-ablation
Cancer Research UK – Trans arterial embolisation (TAE) for neuroendocrine tumours (NETs)
https://www.cancerresearchuk.org/about-cancer/neuroendocrine-tumours-nets/treatment/tae
American Cancer Society – Ablation or Embolization for PNETs
https://www.cancer.org/cancer/types/pancreatic-neuroendocrine-tumor/treating/ablative-techniques.html
Journal of Experimental & Clinical Cancer Research – Hepatic arterial embolization in patients with neuroendocrine tumors
This study evaluates the effectiveness of hepatic arterial embolization in patients with NETs.
https://jeccr.biomedcentral.com/articles/10.1186/1756-9966-33-43
Endovascular Today – Transarterial Treatment of Liver Metastatic Neuroendocrine Tumors https://evtoday.com/articles/2015-oct/transarterial-treatment-of-liver-metastatic-neuroendocrine-tumors
ScienceDirect – Transarterial radioembolization in neuroendocrine liver metastases
https://www.sciencedirect.com/science/article/pii/S104084282500085X
Cancer Research UK – Trans arterial embolisation (TAE) for neuroendocrine tumours (NETs)
https://www.cancerresearchuk.org/about-cancer/neuroendocrine-tumours-nets/treatment/tae
Cleveland Clinic – Transarterial Chemoembolization (TACE)
https://my.clevelandclinic.org/health/treatments/23403-chemoembolization
Journal of Nuclear Medicine – Radioembolization Versus Bland or Chemoembolization for Liver-Dominant Metastatic Neuroendocrine Tumors
https://jnm.snmjournals.org/content/62/12/1669
Penn Medicine – Liver-Directed Therapy for NETs
https://www.pennmedicine.org/cancer/types-of-cancer/neuroendocrine-tumors/neuroendocrine-tumors-treatment/liver-directed-therapy
