Loading In research published on Tuesday in the prestigious Nature journal, researchers from Melbourne’s Peter Doherty Institute and Telethon Kids Institute revealed they had discovered that the T cells had the ability to halt the growth of melanoma cells. The cells were able to control the tumour in mice for the life of the animal, which was likely to equate to decades of protection in humans, said the paper’s lead author Simone Park. “What we found was that the cells are capable of basically inducing a state of dormancy of the tumour, like putting the cancer to sleep,” Ms Park said.

“The cancer cells aren’t completely killed. They are still there, but they are held in check by the tissue-resident memory T cells.” Ms Park, a PhD student with the University of Melbourne, said the breakthrough was made using a novel system whereby scientists were able to monitor melanoma cells and T cells under the microscope using fluorescent markers. “What we could see was that the T cells were constantly patrolling the skin and watching over these melanoma tumour cells,” she said. Tissue-resident memory T cells (in green) are pictured watching over melanoma cells (in red). The scientists were also able to remove the T cells from mice with dormant melanomas and found that once the cells were gone the tumours were then able to escape or grow, highlighting the importance of the immune cells in controlling the spread of cancer.

Melanoma remains the fourth most commonly diagnosed cancer in Australia, behind breast cancer, prostate cancer and colorectal cancer. Australia and New Zealand have the world's highest incidence rate for melanoma. Although it has a promising survival rate of more than 90 per cent at five years, it still kills an estimated 1900 Australians every year, most of them men. This year it is expected that a further 14,320 Australians will be diagnosed with the skin cancer. Ms Park said it was hoped that the research could help lead to better treatment for melanoma tumours in the future. “By showing these cells are important for controlling cancer … we’ve shown that they are going to be good targets for future design of immunotherapy,” she said.