The NSW government is hoping to recruit up to 330 people for a world-first trial testing the use of medicinal cannabis to treat chemotherapy patients.

If 21-year-old Matilda had her choice, she would have no difficulty tucking into a honey-glazed ham or mango pavlova this Christmas.

But with more than five months left of nausea-inducing chemotherapy treatment ahead for the recently-diagnosed cancer patient, the very thought of food is already making her feel sick.

"The nausea from the drugs means I can't keep my food down so I have no appetite," she said.

"It's really irritating because I also get diarrhoea from that chemotherapy, so I lose my appetite and then I want to eat but I can't eat whatever I want because of the diarrhoea".

Matilda, who is being treated for soft tissue sarcoma cancer, is now hoping to be one of 80 people chosen to take part in a NSW government trial testing the use of medicinal cannabis to treat chemotherapy patients.

The marijuana-derived tablet will initially be trialled on 80 patients at 10 cancer centres across Sydney and in Orange, in the state's central west, with plans to extend it to a further 250 people if the results are positive.

"Despite significant advances in treatment, we know that more than a third of patients receiving potent, intravenous chemotherapy still suffer from nausea and vomiting," NSW Medical Research Minister Pru Goward said on Monday.

"So we are taking a very evidence-based scientific approach, supported by doctors and clinicians, which I think offers us the best hope for patients."

Associate Professor Peter Grimison from Chris O'Brien Lifehouse, who will lead the research, said doctors would be progressing carefully to ensure the trial is properly conducted.

"The eyes of the world will be upon this pioneering trial," he said.

Chemotherapy patients at both the early and late stages of cancer will be eligible but those with a history of kidney or liver problems or psychotic illness will be ruled out.

Prof Grimison believes less than a quarter of his patients currently self-medicate with cannabis.

Those cancer sufferers won't be able to take part in the trial.

The jury is still out on whether cannabis-derived medicines actually work to relieve symptoms, Prof Grimison said, adding that a market shelf drug is not likely for a few years.

"This gives hope that we can improve their suffering and relieves symptoms but we actually need to prove it works before it's widely available," he said.

"If it doesn't work then we may be better finding a better treatment."