A man with advanced prostate cancer is believed to be cured after doctors 'shocked' his tumour to death with huge amounts of testosterone.

The result has been described as 'unexpected' and 'exciting' because most prostate cancer therapies work by depriving tumours of testosterone, because cancer uses it as a fuel.

Other seriously ill men taking part in the same trial showed responses that astounded scientists, with tumours shrinking and the progress of their disease halted.

Levels of Prostate Specific Antigen (PSA), a blood marker used to monitor prostate cancer, also fell in the majority of the 47 participants.

One individual whose PSA levels dropped to zero after three months and shows no remaining trace of the disease after 22 cycles of treatment appears to be cured, said the researchers.

Professor Sam Denmeade, from Johns Hopkins University School of Medicine in Baltimore, US, who led the study, said: ""Our goal is to shock the cancer cells by exposing them rapidly to very high followed by very low levels of testosterone in the blood. The results are unexpected and exciting.

"We are still in the early stages of figuring out how this works and how to incorporate it into the treatment paradigm for prostate cancer.