Image Guided Treatment of Kidney Cancer

With the advent of Interventional Oncology and tumour ablation, patients with renal (kidney) cancer now have access to a range of highly effective minimally invasive treatment options.

Until recently the only treatment options for kidney cancer were active monitoring and / or radical nephrectomy, where the entire kidney is removed. The latest image guided techniques mean that it is now possible to specifically target the tumour and immediate surrounding tissues, without the need to remove the entire organ. This preserves kidney function, reduces surgical risk and gives a quicker recovery time.


Introduction to Treating Kidney Cancer

The management of kidney tumours has changed dramatically over the last twenty years. Previously, any solid lump discovered in the kidney would either be repeatedly scanned and monitored or removed with the entire kidney – a ‘radical nephrectomy’. As surgical techniques have developed, it has become possible to remove the kidney tumour and only part of the kidney – a ‘partial nephrectomy’ - often performing this surgery through a keyhole method. These advances have allowed for faster recovery and the preservation of the kidney function. However, as the tissues from around the kidney are physically dissected and the kidney cut into there remains a significant risk of bleeding and conversion of the keyhole procedure to an ‘open’ one.

Over the same twenty years, there have also been enormous advances in imaging and alternative methods of tissue destruction that are even less invasive than keyhole surgery.

Advances in Kidney Cancer Treatment

The advances in imaging have had an impact on the detection and treatment of kidney tumours in two ways. Firstly, the number of small kidney tumours detected has risen dramatically. This is because scans themselves are easier to obtain and because the resolution of ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) have improved so much that smaller kidney tumours can now be detected. Often people find themselves diagnosed with a kidney tumour when in fact they had imaging for completely unrelated symptoms.

Secondly, the advances in imaging allow the accurate guidance of needles into tumours and the monitoring of tumour treatment in real time.

The role of Kidney Biopsy

Taking a small sample of tissue is known as a biopsy. This can be performed through a needle that is guided to the target with imaging. As imaging has improved, the accuracy of biopsy has also improved, with a diagnostic sample of tissue obtained over nine times out of ten. Consequently, more patients are undergoing a biopsy of their renal tumour before any treatment takes place to characterise the lump in greater detail, sometimes avoiding the need for any intervention at all if the sample returns a benign tumour.

Image-guided Treatments for Kidney Cancer

In the same way that tissue samples may be obtained by a thin needle inserted through the skin and into a tumour, similar needles may be inserted to deliver energy directly into the tumour to destroy it and a small margin of healthy kidney tissue. This procedure, known as ‘ablation’ refers to any non-radiotherapy form of treatment that destroys tissue focally, while sparing the surrounding healthy tissue. The body then turns the treated tumour naturally into a scar using the immune system.

Interventional Oncology

The decision to proceed with ablation is taken within the context of a multidisciplinary team comprising treating clinican, surgeon and oncologist. Although the treating clinician is often a Radiologist, this field of image guided direct tumour treatment has been termed ‘Interventional Oncology’.

When Should Kidney Cancer be Ablated?

Ablation is suitable in cases where:

  •           The patient does not wish to undergo surgery
  • ·         The patient is deemed unfit / high risk for surgery
  • ·         There is a solitary kidney or poor renal function
  • ·         There are bilateral tumours or a genetic predisposition to multiple tumours
  • ·         Tumour position would necessitate a radical nephrectomy, but ablation would be technically feasible

Treatment is carried out in a CT scanner within an operating theatre. Tumours up to 4cm may be treated, as long as they do not lie immediately next to important structures within the middle of the kidney.

The patient is given a general anaesthetic and positioned, usually face down, on the treatment bed. The CT scanner is then used to guide the treatment needles into position within the kidney.

Types of Kidney Tumour Ablation

The most common types of energy generated by the treatment needles are cold or heat. Cold-destruction of tumours, or cryoablation, uses compressed argon gas to create ice within the tumour. As the argon expands within the closed tip of the treatment needle, the temperature in the surrounding tissue drops rapidly to around -100 degrees celcius. This ice-ball expands and can be visualised in real time as it covers the tumour and a small rim of normal kidney. After ten minutes of freezing, the ice ball is thawed by the body’s heat, augmented by a short period of heating induced by the use of pressurised helium expanding down the needle. A further freezing cycle follows, as it has been shown that a double freeze/thaw provides the most effective tumour treatment.

Heat destruction of renal tumours is usually in the form of electricity – radio-frequency ablation, or RFA. An alternating current is delivered down an electrode to a grounding pad, usually placed on the thigh. The current induces molecular friction of charged molecules around the needle tip. This friction is translated into heat that is deposited in the surrounding tissues and denatures the cells. Although both methods may effectively kill tumour cells, cryoablation allows the surgeon to watch the treatment taking place in real time. Ice, rather than heat, can be seen on the CT scans as the treatment takes place. Therefore the clinician can be much more certain that the tumour has been covered adequately.

An overnight stay is usually recommended, as although this treatment is usually very well tolerated there is a small risk of bleeding. After discharge, imaging and clinical follow up is suggested at one month, three months and six months after the procedure, and then yearly.

A recent review of the medical literature looking at these types of treatment has shown that there is less chance of local tumour recurrence with cryoablation than with RFA, and this is reflected in the National Institute for Health and Clinical Excellence (NICE) guidelines supporting this treatment. In fact the most recent series published in the medical literature suggest that there is now little difference in long term cancer outcomes between cryoablation and minimally invasive surgery.


The management of kidney tumours is changing. Biopsies are being requested more frequently, in order to confirm a diagnosis of cancer before treatment.

Image-guided cryoablation is very exciting as it offers patients with kidney tumours a genuine alternative from the traditional ‘observation versus surgery’ approach. In particular older patients, or those who would tolerate surgery less well, may find this treatment to be an excellent way of managing an asymptomatic small kidney tumour.

The Benefits of Kidney Tumour Ablation are clear:

  •        The treatment may be performed with only an overnight stay.
  •        Being minimally invasive, tumour ablation is very well tolerated.
  •        Ablation leaves a functioning kidney in place - as the treatment is so targeted.
A medication that reduces sensation. Full medical glossary
Not dangerous, usually applied to a tumour that is not malignant. Full medical glossary
On both sides of the body Full medical glossary
The removal of a small sample of cells or tissue so that it may be examined under a microscope. The term may also refer to the tissue sample itself. Full medical glossary
Abnormal, uncontrolled cell division resulting in a malignant tumour that may invade surrounding tissues or spread to distant parts of the body. Full medical glossary
The basic unit of all living organisms. Full medical glossary
The abbreviation for computed tomography, a scan that generates a series of cross-sectional x-ray images Full medical glossary
The process of determining which condition a patient may have. Full medical glossary
The basic unit of genetic material carried on chromosomes. Full medical glossary
Relating to the genes, the basic units of genetic material. Full medical glossary
intermittent claudication Full medical glossary
The organs specialised to fight infection. Full medical glossary
A type of minimally invasive surgery. Full medical glossary
One of two bean-shaped organs that are located on either side of the body, below the ribcage. The main role of the kidneys is to filter out waste products from the blood. Full medical glossary
A large abdominal organ that has many important roles including the production of bile and clotting factors, detoxification, and the metabolism of proteins, carbohydrates and fats. Full medical glossary
A technique for imaging the body that uses electromagnetic waves and a strong magnetic field. Full medical glossary
A type of surgery that aims to limit the amount of trauma to the patient; for example, keyhole surgery. Abbreviated to MIS. Full medical glossary
An abbreviation for magnetic resonance imaging, a technique for imaging the body that uses electromagnetic waves and a strong magnetic field. Full medical glossary
Relating to a group of healthcare professionals with different areas of specialisation. Full medical glossary
The surgical removal of a kidney. Full medical glossary
A specialist in the treatment of cancer. Full medical glossary
The treatment of disease using radiation. Full medical glossary
Relating to the kidney. Full medical glossary
A group of cells with a similar structure and a specialised function. Full medical glossary
An abnormal swelling. Full medical glossary
A diagnostic method in which very high frequency sound waves are passed into the body and the reflective echoes analysed to build a picture of the internal organs – or of the foetus in the uterus. Full medical glossary
Relating to the sense of sight (vision). Full medical glossary