Italian businessman Innocente Marcolini, 60, fell ill after using a handset at work for up to six hours every day for 12 years.
Now Italy’s Supreme Court in Rome has blamed his phone. Experts have predicted a flood of legal actions from victims.
Stricken Mr Marcolini last night warned: “People must be told the risks.”
He was diagnosed with a brain tumour after complaining of head and chin pains.
And yesterday his country’s Supreme Court stated there was a “causal link” between his heavy phone use and the growth.
British scientists have claimed there is insufficient evidence to prove any link to mobiles.
But after the Rome court ruling, Mr Marcolini said: “This is significant for very many people. I wanted this problem to become public because many people still do not know the risks.
“I was on the phone, usually the mobile, for at least five or six hours every day at work. I wanted it recognised that there was a link between my illness and the use of mobile and cordless phones.
“Parents need to know their children are at risk of this illness.”
Respected oncologist and professor of environmental mutagenesis Angelo Gino Levis gave evidence for Mr Marcolini — along with neurosurgeon Dr Giuseppe Grasso.
They said electromagnetic radiation emitted by mobile and cordless phones can damage cells, making tumours more likely. Prof Levis told The Sun: “The court decision is extremely important. It finally officially recognises the link.
“It’ll open not a road but a motorway to legal actions by victims. We’re considering a class action.
“Tumours due to radiation may not appear for 15 years, so three to five-year studies don’t find them.
“We’ll only realise in years to come the damage phones can cause children.” Mr Marcolini’s tumour was discovered in the trigeminal nerve — close to where the phone touched his head. It is benign but threatened to kill him as it spread to the carotid artery, the major vessel carrying blood to his brain.