The discovery comes after a 28-year-old Japanese mother was diagnosed with leukaemia shortly after she gave birth in 2006. Barely a year later, three months after the
woman had died, her daughter was diagnosed with the same blood disease.
Samples of the baby's blood and those of the mother were examined using "genetic fingerprinting", which showed that both contained exactly the same rogue cancer cells.
Doctors are baffled, as this is the first report of mothers transmitting cancer to their unborn children. Normally the immune system of a baby in the womb would
destroy invasive cancer cells.
Closer investigation revealed that the daughter's leukaemia cells were missing a vital piece of DNA that would have flagged them up as 'intruders' to her immune system. Without this, her system was unable to target and destroy th cancer cells and she went on to develop the disease.
Professor Mel Greaves, who led a study regarding this phenomenon at the Institute of Cancer Research in Sutton, the UK, said: "It appears that in this case and, we presume, other cases of mother to offspring cancer, the maternal cancer cells did cross the placenta into the developing foetus and succeeded in implanting because they were invisible to the child's immune system."
He added: "We stress that such mother to offspring transfer of cancer is exceedingly rare and the chances of any pregnant woman with cancer passing it on to her child are remote."
