**3. High temperature ablative techniques**

Cancer cells are very sensitive to both very high and low temperature. Radiofrequency and microwave energies use the concept of high temperature (above 55°C). Thermal ablation causes denaturation of cellular proteins and vascular necrosis of tumour cells resulting in instantaneous cellular death.

#### **3.1. Radiofrequency ablation**

#### *3.1.1. Mode of action*

Electric current passes through radiofrequency ablation (RFA) probe/electrode into tumour creating closed loop circuit with a generator and grounding pads. The current triggers disruption of intracellular ions and friction between molecules producing heat. The electromagnetic field generates high temperature typically above 55°C. The generated heat results in cytotoxic effect and instantaneous cell death occurring with temperature reaching 60°C [18].

**3.3. Possible side effects of high thermal ablative techniques**

• Haematuria and peri-nephric haematoma are usually self-limiting.

• Acute tubular necrosis and decreases overall renal function [22].

65–85% and cancer specific survival rate of 88–97.9% [23–25].

CT scan is suggested thereafter for a period up to 7 years.

**4. Investigational and experimental treatments**

**4.1. Laser interstitial thermal therapy (LITT)**

the heat particularly close to the larger vessels.

• Skin burns (mainly with radio-frequency ablation).

psoas major muscle.

• Calyceocutaneous fistulae.

**3.4. Oncological efficacy**

**3.5. Monitoring and follow up**

• Infection and abscess formation.

myalgia.

• Heat sink effect: kidney is well perfused organ. this may result in unequal distribution of

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• Thermal injury to neighbouring structures such as bowels, ureter, genitofemoral nerve and

• Post-ablation syndrome: the syndrome is usually self-limiting. Patients might suffer symptoms of low-grade fever (37.5–38.5°C), delayed pain, nausea, vomiting, malaise, and

Few studies have evaluated the short and intermediate oncological outcomes. The technical success rate has been reported to be 95.5–98.5%. The average need for repeat treatment is thought to be around 3%. Small renal tumours (<3 cm) and exophytic location were independent factors for successful treatment. The overall 5 year survival rate was reported between

Most urological institutions recommend contrast enhanced CT scan at 3 months to evaluate treatment success. Follow-up CT scan is suggested every 6 months for the first 2 years. Annual

This treatment modality is currently being evaluated for treatment of solid tumours including brain, pancreatic, breast, thyroid and prostate cancer. LITT utilizes image guided low voltage laser probes to deliver heat and destroy target tissue. Optical fibres are inserted directly to the target tissue. Laser light delivers heat that is converted to heat. The emitted light energy from

• Hyper adrenal crisis is very rare. This might be secondary to adrenal thermal injury.

#### *3.1.2. Technique*

Small renal masses (≤3 cm) can be treated with single cycle of RFA. However, larger tumours (up to 5 cm) might be suitable for treatment using overlapping cycles technique. RFA achieves excellent results in treating exophytic and endophytic tumours.

RFA is carried out under general anaesthetic or conscious sedation. Different types of RFA electrodes could be used including; single tip, multi-tined expandable electrodes, or a cluster tip electrode. RFA electrodes are inserted into the tumour under CT/MRI or ultrasound guidance. Hydro-dissection can be used if the tumour is adjacent to bowel segment.

Once electrodes are positioned; a 12 min cycle is delivered. Some RFA systems use internal cooled electrodes to avoid adjacent tissue carbonization. This method might have an impact on heat distribution to distant area of the tumour and subsequently might affect the efficacy of treatment [19, 20].

### **3.2. Microwave ablation**

#### *3.2.1. Mode of action*

Microwave ablation uses the same concept of thermal ablation as RFA technique. Thermal ablation results in coagulative necrosis of tumour cells. Microwave ablation uses different energy source. It produces an electromagnetic spectrum with frequency of 900–2450 MHz. The oscillating microwave field causes polarisation of molecules resulting in increased kinetic energy producing heat.

Microwave ablation has several advantages over radiofrequency ablation. It is possible to treat larger tumours without the need of overlapping treatments. Microwave ablation does not cause charring effect. Skin pads are not required during microwave ablation treatment; therefore the risk of skin burns is minimal.

#### *3.2.2. Technique*

Two microwave antennae are inserted under CT or ultrasound guidance. A fibre-optic thermal sensor inserted at the periphery of the tumour to provide continuous temperature monitoring. It is recommended to delivers 3 cycles achieving temperature of 60°C. Each cycle lasts for 20 min [21].

#### **3.3. Possible side effects of high thermal ablative techniques**


**3.1. Radiofrequency ablation**

Electric current passes through radiofrequency ablation (RFA) probe/electrode into tumour creating closed loop circuit with a generator and grounding pads. The current triggers disruption of intracellular ions and friction between molecules producing heat. The electromagnetic field generates high temperature typically above 55°C. The generated heat results in cytotoxic

Small renal masses (≤3 cm) can be treated with single cycle of RFA. However, larger tumours (up to 5 cm) might be suitable for treatment using overlapping cycles technique. RFA achieves

RFA is carried out under general anaesthetic or conscious sedation. Different types of RFA electrodes could be used including; single tip, multi-tined expandable electrodes, or a cluster tip electrode. RFA electrodes are inserted into the tumour under CT/MRI or ultrasound guid-

Once electrodes are positioned; a 12 min cycle is delivered. Some RFA systems use internal cooled electrodes to avoid adjacent tissue carbonization. This method might have an impact on heat distribution to distant area of the tumour and subsequently might affect the efficacy

Microwave ablation uses the same concept of thermal ablation as RFA technique. Thermal ablation results in coagulative necrosis of tumour cells. Microwave ablation uses different energy source. It produces an electromagnetic spectrum with frequency of 900–2450 MHz. The oscillating microwave field causes polarisation of molecules resulting in increased kinetic

Microwave ablation has several advantages over radiofrequency ablation. It is possible to treat larger tumours without the need of overlapping treatments. Microwave ablation does not cause charring effect. Skin pads are not required during microwave ablation treatment;

Two microwave antennae are inserted under CT or ultrasound guidance. A fibre-optic thermal sensor inserted at the periphery of the tumour to provide continuous temperature monitoring. It is recommended to delivers 3 cycles achieving temperature of 60°C. Each cycle lasts for 20 min [21].

effect and instantaneous cell death occurring with temperature reaching 60°C [18].

ance. Hydro-dissection can be used if the tumour is adjacent to bowel segment.

excellent results in treating exophytic and endophytic tumours.

*3.1.1. Mode of action*

216 Evolving Trends in Kidney Cancer

*3.1.2. Technique*

of treatment [19, 20].

*3.2.1. Mode of action*

**3.2. Microwave ablation**

energy producing heat.

*3.2.2. Technique*

therefore the risk of skin burns is minimal.


#### **3.4. Oncological efficacy**

Few studies have evaluated the short and intermediate oncological outcomes. The technical success rate has been reported to be 95.5–98.5%. The average need for repeat treatment is thought to be around 3%. Small renal tumours (<3 cm) and exophytic location were independent factors for successful treatment. The overall 5 year survival rate was reported between 65–85% and cancer specific survival rate of 88–97.9% [23–25].

#### **3.5. Monitoring and follow up**

Most urological institutions recommend contrast enhanced CT scan at 3 months to evaluate treatment success. Follow-up CT scan is suggested every 6 months for the first 2 years. Annual CT scan is suggested thereafter for a period up to 7 years.
