By Tim Murphy

The greenshell mussel seems to be proving a little too hot to handle for the doctors and drug company who announced its cancer-fighting potential to the world.

As its commercial offshoot, lyprinol, met obstacles yesterday from the Ministry of Health, the mussel men were pulling back from statements and promises they made last week.

The link between mussels and a possible treatment for cancer was revealed on Friday in a statement from Queen Elizabeth Hospital, Adelaide, in the name of Dr Henry Betts and titled: "Cancer - Hope from the Sea."

The scientist, the main researcher into the mussels' cancer-fighting qualities, said lyprinol had "the potential for remarkable anti-cancer action."

He felt 90 per cent sure that the extract would work.

But last night, after the Ministry of Health and cancer societies in New Zealand and Australia had questioned the claims surrounding the product, Dr Betts was backing away from his earlier views.

"It's a great concern of mine to even suggest that there is any evidence that it is effective in treating human cancers," he said.

"We've not made that claim at all. What we're saying is there is evidence it may be effective and we are launching clinical trials in Adelaide to find out if that is the case or not."

Criticism yesterday by Prime Minister Jenny Shipley of the timing of the research announcement so close to the New Zealand launch of lyprinol also saw a change in tack by John Waitzer, managing director of the product's maker, Pharmalink.

It was Mr Waitzer who arranged last week for TVNZ to make the worldwide announcement of the mussel's potential - to run on One Network News and Holmes tonight. The TV firm was hosted in Adelaide last Thursday under this arrangement.

Mr Waitzer attempted to lock the New Zealand Herald into a similar agreement, with all details to be kept secret until Pharmalink determined, but that offer was declined. Independent inquiries by the Herald last Friday subsequently prompted TVNZ to screen the Waitzer material that night - four days early.

Mr Waitzer had threatened the Herald with legal action if any details of the research were published before he was ready - and said he had "shut down" the hospital staff and even Food and Fibre Minister John Luxton to prevent them from talking.

Last night, responding to Mrs Shipley's allegations of media manipulation, Mr Waitzer said there was no way he would have been able to control the Queen Elizabeth doctors commenting on the research.

However, a "journalistic adviser" acting for him, Desmond Zwar, wrote to the Herald last Friday offering exclusive interviews with the doctors and scientists involved - as long as the newspaper agreed to an embargo. He claimed to be able to offer exclusive details of results of the hospital's cancer trial once the mussel extract had been tested on patients.

Mr Waitzer had earlier talked up lyprinol's potential for success.

"This is big. All cancers. They've tried it on lung cancer, breast, prostate. There's about 300 cancers they've tried it on. They kill all the cancer and it's a food that's done it."