Why some cancers return11th August 2008
Researchers have found what they believe is the mechanism through which dormant cancer cells "recur" in the body, seeding new tumours that spread to other organs in a process known as metastasis.
It has long been known that metastatic tumour cells can begin growing again after long periods of inactivity.
Scientists found that the switch from dormancy to proliferative, metastatic growth may be regulated, in part, through signaling from the surrounding micro environment, which leads to changes in the skeletal architecture of dormant tumour cells.
The study, funded by the National Cancer Institute and published in the journal Cancer Research, may pave the way for strategies to inhibit the switch from dormancy to proliferation by targeting this mechanism.
The recurrence of breast cancer often follows a long latent period in which there are no signs of cancer, and metastases may not become clinically apparent until many years after removal of the primary tumour and follow-up therapy.
Recent evidence suggests that, in many cases, tumour cells have already seeded metastatic sites even when the primary tumour is diagnosed at an early stage, according to Jeffrey Green, one of the lead researchers of this study.
Green said that approximately 30% of breast cancer patients diagnosed with early-stage disease have been found to have breast cancer cells in their bone marrow, which do not manifest themselves clinically in any way.
While not all of these disseminated tumour cells survive long, some of them could be dormant but viable cells that could begin to proliferate years later.
These dormant cells can be resistant to conventional therapies, such as chemotherapy, that target actively dividing cells; such cells could account for disease recurrence after apparently successful treatment of primary tumours.
Blood supply is one of the key factors in the immediate micro-environment surrounding dormant tumour cells which affects whether it switches to become active or not, the study found.
Signals from neighbouring cells can also have an effect.
Green called for further studies to discover new ways to therapeutically keep the dormant-to-active switch in the 'off' position, thus limiting the likelihood of metastasis in later life.
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Title: Why some cancers return
Author: Luisetta Mudie
Article Id: 7850
Date Added: 11th Aug 2008