A surprise discovery has raised hopes a particular type of immunotherapy may be an effective treatment for stomach cancer.

Australian scientists may have discovered a new way to treat deadly stomach cancer, a disease that strikes down twice as many men as women.

A study, recently published in journal Immunity, has shown switching off a gene called NF-kB1 led to spontaneous development of stomach cancer caused by chronic inflammation.

Dr Lorraine O'Reilly of the Walter and Eliza Hall Institute and University of Melbourne says the finding was unexpected because it had been thought that abnormally high levels of any of the NF-kB proteins caused the cancer to grow.

But it now appears that the 'odd one out' in the family of NF-kB proteins could be key to treating stomach cancer.

"It is well established that long-term inflammation can lead to stomach cancer in humans. The cellular processes that we have identified in this study as being important for the development of stomach cancer provide new targets for therapy that have not been explored before," Dr O'Reilly said.

Around 2000 cases of stomach cancer are diagnosed in Australia each year, many of which are fatal. In 2015 it killed 1150 people.

Co-investigator Dr Tracy Putoczki believes the new research provides "compelling" evidence that immunotherapy could be an effective weapon against the disease.

Immunotherapy - a type of drug treatment that focuses on using the body's own immune system to attack cancer cells - has been shown as an effective treatment for melanoma, advanced lung cancer, kidney cancer and Hodgkin lymphoma.

However the research on its use in stomach cancer still remains in its infancy, said Dr Putoczki.

"We showed that there are markers on these stomach tumour cells that indicate they would be responsive to a type of immunotherapy called immune checkpoint inhibitors, in particular anti-PDL1 immunotherapy, which is already used with great success in the treatment of melanoma and certain other cancers," said Dr Putoczki.