RENAL TUMOUR ABLATION
RENAL TUMOUR ABLATION
Traditionally, renal cancer has been treated by a combination of surgery, radiotherapy and chemotherapy. Thermal ablation is relatively new technique, which involves the destruction of cancer cells using thermal (heat and cold) energy. Small needles are inserted into the tumour under image control, typically using ultrasound and CT scanners. The needles are heated or cooled to cause irreversible thermal damage and eventual destruction of the cancer cells. Ablation targets the cancer with a safe margin that is able to preserve the maximal amount of normal kidney tissue. The dead tissue does not need to be removed by surgery.
Generally, these types of treatment are used for small renal tumours, usually between 2 to 5cm in diameter as advised by NICE. However, several other factors are considered when actually deciding upon best treatment option for the renal tumour. Such factors include the location of the tumour, the surrounding structures close to the tumour, your overall health, how well your kidneys are functioning, surgery and patient preference. There are a number of different thermal energies available all with slightly different benefits and disadvantages which can be discussed in an outpatients appointment. The main thermal energies used are:
- Cryoablation (CRYO): Involves the use of ice to freeze tumours at temperatures less than -40 °C and provides a very efficient means of destroying tumour cells in a localised area.
- Microwave ablation (MWA): Electromagnetic microwaves from a generator agitate water molecules in the surrounding tissue. This produces heat, which kills the diseased tissue. Microwave allows for higher temperatures, larger tumor ablation volumes and faster ablation times.
- Radiofrequency ablation (RFA): Radiofrequency waves are passed through the needle, causing the molecules around the needle tip to vibrate. This imparts heat and friction to the area and kills the diseased tissue.
What is a Renal Ablation Procedure?
Renal ablation is a minimally invasive procedure using imaging to guide the placement of small needles into the renal tumour via the skin (percutaneously). Ultrasound and CT are used to guide the needles into the exact location away from any important structures prior to the administration of thermal energy. An area of normal kidney tissue around the tumour will be targeted, as it is known that this area may contain microscopic tumour cells that are not visible on a scan. This reduces the risk of recurrence. The procedure is typically performed under a general anaesthetic in the prone (lying on your front) or lateral (lying on your side) position in the CT scanner. The procedure can take up to 2 or 3 hours depending on the individual patient.
Renal ablation is a safe and effective procedure, but as with any medical procedure there are some risks and complications that can arise. Structures in or adjacent to the kidney may be damaged. The commonest risks are bleeding, bowel perforation, renal impairment or damage to the kidney collecting system. Such damage is usually apparent on the post-procedure scan and can be dealt with promptly usually with percutaneous techniques but very occasionally requires surgery. There is a small risk of recurrence of the tumour after an ablation. The exact risk varies from patient to patient and follow-up CT scans to examine the ablated area will be undertaken.
When will a patient need renal ablation procedure performed ?
It is a multidisciplinary decision to perform renal ablation with your urologist and myself discussing your case with regards all the potential options from surgery, chemotherapy and renal ablation. You will have an opportunity to see your urologist and myself to discuss all the available options and allow you to make an informed choice as to what is best for you. CT and / or MRI scanning will have been performed previously to confirm the diagnosis and assess cancer growth. Occasionally we may perform a biopsy to grade the tumour and this will help in deciding the best form of treatment in your case.
What happens during a Renal Ablation Procedure?
The procedure is performed under a general anaesthetic within the CT department. You will be scanned again routinely as part of the procedure. This allows us to further plan the treatment and confirm the best means of access to the tumour. Usually, this is done with you lying on your front or on your side. Using the scans, the point of entry for the needles is marked on the skin. The area of the skin to be used is cleaned with antiseptic solution and local anaesthetic used to numb the skin. A biopsy of the area may be taken prior to the needles being inserted, and then the needles are guided into the tumour, using the CT/Ultrasound to ensure they are correctly targeted. The ablation is then undertaken, with possibly several areas being targeted and the needles being manipulated several times. A completion scan is then performed to assess the immediate results of the ablation therapy. The procedure can take up to 2 or 3 hours depending on the individual patient.
How should I prepare?
The procedure will be carried out under general anaesthesic. You will be admitted on the day of the procedure and generally stay a single night in hospital. You will be asked not to eat or drink for 4hrs before the procedure. If you have any allergies or have previously had a reaction to the dye (contrast agent), you must tell the radiology staff before you have the test.