Melbourne scientists have discovered a breakthrough treatment that could suppress the growth of gastric tumours.

There's new hope for patients with stomach and bowel cancer after Melbourne scientists discovered a way to suppress the growth of tumours.

Scientists at the Olivia Newton-John Cancer Research Institute have shown that inhibiting a protein called HCK can suspend the growth of established gastrointestinal tumours and reduce the emergence of new cancers.

Lead researcher Matthias Ernst said HCK had a powerful role in cancer development because of the effect it has on "garbage collector" macrophage cells.

"These cells remove unwanted debris or damaged cells, or they can behave like 'nurses' to help at sites of injury and wounding," Professor Ernst said on Wednesday.

"What we've now discovered is the more HCK activity a macrophage has, the more it nurtures cancer cell growth and survival."

In preclinical trials, drugs that modify the behaviour of macrophages were already starting to show promise as a treatment for solid tumours - and could stop the growth of bowel and gastric cancers.

Gastric cancers affect more than 15,000 Australians each year and are among the most common causes of cancer death.