The finding radically alters the view that cancer cells spread only at late stages of cancer.
Researchers found that even before cancer is diagnosed, breakaway cancer cells head off to infiltrate other bodily organs.
They may lie dormant in other parts of the body for years before starting to grow.
But because they split from the original cancer cells very early on they may not respond to the same treatment as the tumour – as may have mutated so much in the intervening time it is in effect a different cancer.
The findings, published in Nature, highlight the seriousness of very early stages of cancer – and also explains how some people develop secondary cancers without a primary tumour being found.
It had been thought that it is when cancer is at its most advanced or at ‘stage 4’ or ‘invasive’ that it is at the greatest risk of it spreading.
The new findings show breast cancer spreads at ‘stage 0’ – before a tumour has been found and cancer has been diagnosed.
The spread of cancer is the cause of death in the vast majority of breast cancer cases and is one of the key problems in treating the disease.
Researchers found that even before breast cancer is diagnosed, breakaway cancer cells head off to infiltrate other bodily organs
Julio Aguirre-Ghiso, professor of haematology at the Icahn School of Medicine, New York said: ‘This research provides insight into the mechanisms of early cancer spread and may shed light into unexplained phenomena.
‘Among them, why as many as 5 per cent of cancer patients worldwide have cancer metastases but no original tumour, and most importantly, why it is so difficult to treat cancer that has spread.’
‘Biologically, this new model of early metastasis challenges everything we thought we knew about how cancer spreads and forms metastasis.
‘It feels like we are going to have to adjust our ideas about the subject of metastasis.’
The research also casts light on the puzzle of why cancer cells spread.
They may lie dormant in other parts of the body for years before starting to grow, meaning the tumours won’t appear on medical scans
They found that cancer ‘hijacks’ a normal program in the gene that helps mammary cells move through the mammary gland, hollow out a tubular, branching network of milk ducts that flow to the nipple.
In the cancer cells, a process which is normally switched off is continually activated – allowing cells to move out of the breast and into the bloodstream, where they spread.
Further research headed by Dr Christoph Klein at the University of Regensburg in Germany,
in an experiment with mice, found 80 per cent of cancer cells that had spread had come from cells breaking off at an early stage, the equivalent of early breast cancer known as DCIS [Ductal carcinoma in situ].
The findings also go to explain why in some cases of very early breast cancer 2-3 per cent of women die of metastasis without ever developing a primary tumour. Dr Klein said: ‘The best explanation for this phenomenon is that early metastasis occurs before or as DCIS develops.
‘A key finding from this second paper is that in the mouse models, 80% of metastasis originated from the early spread cells and not from the large tumours.’
The authors believe that these mechanisms could apply in early dissemination and metastasis in other human cancers, including melanoma and pancreatic cancer.
Dr Justine Alford, Cancer Research UK’s science information officer, said: ‘Breast cancer survival has doubled in the last 40 years in the UK, but some patients’ diseases are harder to treat because their cancer has spread.
‘This important early study sheds light on how and when this process can happen in mice with a certain type of breast cancer.
‘Further studies are needed to see if the same processes happen in people, which one day could help scientists develop better ways to tackle the disease in women whose cancer has spread.’
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Written by Colin Fernandez, Science Correspondent and published by The Daily Mail ~ December 14, 2016.
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