How can you tell how bad a cancer is, and how likely the patient is to survive? New evidence suggests that the best way may sometimes be to look at how well the immune system has attacked tumours, rather than focussing on how far the tumours have spread. It has long been known that the immune system can home in on cancerous cells and that immune cells can take up residence within tumours. But it hasn’t been clear whether such cells have much of an impact on the progress of the disease.
A study by Jérôme Galon, Franck Pagés, and a team of researchers at INSERM in Paris, France, has brought the significance of these immune-system invaders to light. “We found that there is an importance of natural anti-tumour immunity against human cancer,” says Galon. Whether a cancer recurs or not after treatment, he adds, may have more to do with the immune system than with the tumour itself. Even patients with small tumours that have not spread, says Galon, will have a bad prognosis if they have a weak immune response to the cancer.