Hong Kong liver cancer patient Mr Chan* said his tumour disappeared following a painless ultrasound treatment that felt similar to “taking a nap”.

The 68-year-old retiree, who had been battling liver cancer since 2013, was among 26 patients who had received a histotripsy treatment conducted by the Chinese University of Hong Kong since April this year.

“There was no pain at all. It was just like taking a nap,” Chan said. “I could be discharged the next day and lead a normal life afterwards. The others may not even know I underwent treatment if I did not tell them.”

Last year, tycoon Li Ka-shing donated three histotripsy machines, each worth US$3 million, to the medical schools of Chinese University and the University of Hong Kong (HKU), and to the Hong Kong Sanatorium and Hospital.

Histotripsy, developed by the University of Michigan, is a non-invasive procedure that uses focused ultrasound waves to disrupt and liquefy liver tumours without the need for surgery or incisions.

In the past, Chan had received multiple treatments, including the removal of his right lobe of liver, microwave and radiofrequency ablations – heat-based treatments that used different types of energy to destroy cancer cells.