**Author details**

laser fibres is absorbed and converted to heat. This would result in thermal destruction of the cancer cells [26]. Neodymium: yttrium-aluminium-garnet (Nd:YAG) laser has been used to treat small renal tumours. All reports are based on small number of treated patients with

The therapeutic use of the ultrasound to treat cancer was established in the 1970s. The mechanism of HIFU involves mechanical and thermal effects. Some of the acoustic wave is converted to heat once absorbed by the tissue. The thermal phenomenon causes cell death by coagulation necrosis once tissue temperature exceeded the 65°C. The mechanical effect causes

HIFU offers completely trackless non-invasive ablative technology. Treatment session can be lengthy. Several studies reported incomplete treatment when renal tumours were excised following HIFU treatment. Skin burns were reported up to 10% of the patients. Respiratory movement and acoustic interference could impede on delivering treatment accurately. Other limitations to HIFU treatment include limited focal zone depth and inability to monitor treatment progression in real life [30–32]. Recent studies investigated the role of magnetic resonance-guided high intensity focused ultrasound. The results are promising, however it

Laparoscopic HIFU has recently evolved to overcome the challenges related to respiratory

HIFU is considered to be experimental treatment. It could be considered in some selected

In conclusion, ablative therapies have emerged as an alternative option to extirpative surgical treatment. Percutaneous focal ablative therapies represent a valid treatment option especially for high risk patients. Randomised controlled trials are needed to compare treatment out-

short follow up [27, 28]. LITT remains an experimental treatment.

micro-streaming, cavitation and radiation force [29].

movements, targeting tumours and acoustic interference.

comes of PN with focal ablative therapies for small renal masses.

remains experimental [33, 34].

218 Evolving Trends in Kidney Cancer

cases.

**5. Conclusion**

**Conflict of interest**

**Notes/thanks/other declarations**

None declared.

None.

**4.2. Extracorporeal high-intensity focused ultrasonography (HIFU)**

Manar Malki1 \* and Amr Emara2

\*Address all correspondence to: manar.malki@nhs.net

