Dormant cancer cells are actively kept in check by the host's immune system - those that escape go on to develop into clinically detectable tumours. A paper online in Nature identifies a crucial stage in the battle, at which point defences stall the expansion of cancer cells that may have managed to dodge past early immunosurveillance.
Robert Schreiber and co-workers use a mouse model to show that the animal's immune system can keep tumour growth in check over an extended period. Clinicians have suspected the existence of such an 'equilibrium' state, because dormant cancers sometimes take off when inadvertently transferred from a donor to an immunosuppressed recipient during organ transplantation.
This newly discovered staging post could also explain the presence of occult tumour cells - in the prostate, for example - in individuals with no symptoms of disease. Eventually it could be used to devise immunotherapies for tightening control of tumour growth, suggest the authors.
In an accompanying News & Views article, Cornelis Melief comments on the 'startling results' and says they demonstrate that considering cancer as a fatal disease is not always appropriate.
Robert Schreiber (Washington University School of Medicine, St Louis, MO, USA)
Cornelis Melief (Leiden University Medical Center, Netherlands) N&V author
Abstract available online.
(C) Nature press release.
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