A Melbourne-led study will examine whether anaesthetic gas being used on cancer patients having surgery could increase the odds of the disease recurring.

A Melbourne-led study will investigate whether anaesthetic gas given to patients undergoing cancer surgery can fuel the disease to return.

About 5700 patients having lung or colorectal cancer surgery will take part in the five-year international study examining cancer recurrence rates when inhaled anaesthesia gas is used, compared to intravenous anaesthesia.

"It is imperative that this is explored in patient population as there is mounting evidence that surgical therapy and anaesthesia may adversely impact cancer outcomes," chief investigator Professor Bernhard Riedel said on Sunday.

About 60 per cent of patients with these cancers will have a recurrence over five years, he said.

The study will bring together anaesthetists, surgeons, oncologists and research scientists from across the globe and it could lead a change surgical strategies globally.

Previous studies found that mice given anaesthetic gases had a 20 to 25 per cent cancer increased risk of recurrence inside their lungs, compared to those treated with intravenous anaesthesia.

Retrospective studies had found there was a five to 10 per cent recurrence in cancer patients who inhaled the gas, Prof Riedel told reporters at Peter MacCallum Cancer Centre.

"The evidence is not robust. We need to do this study," he said.

"These gases don't cause cancer. These gases add fuel to the fire.

"These volatile agents just add more inflammation and potentially immune suppressants for that brief period. So the underlying risk of having a cancer and maybe ... little spots of cancer that can reoccur is what these volatiles may contribute to."

Surgery is the most common treatment for cancer up to 80 cent of patients with the disease exposed to anaesthetic during treatment, the Australian and New Zealand College of Anaesthetists states.

Inhaled gas has been the primary techniques used by anaesthetists for decades, Prof Riedel noted.

More than 300,000 cancer operations are done in Australia each year and it is expected to increase over the next decade.

With the study results years away, the leading Victorian cancer hospital has already begun reducing its use of the inhaled anaesthesia in some cases.

"(But) having an experienced anaesthetist who knows the technique well is probably more important than trying to try techniques that aren't familiar with them," Prof Riedel said.

"It is not going to cure cancer. It is really a supportive strategy to help the cancer surgeons achieve best outcomes for their patients."