Cancer passed from mother to unborn baby

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Tue 13 October 2009

Extremely rare experts say

UK scientists have proven that cancer cells from a pregnant woman managed to cross the placenta and cause disease in her unborn child.

Although there are 17 recorded cases where the transfer of cancer cells from mother to foetus had been suspected - usually in cases of leukaemia or melanoma - it is thought this is the first time it has been proven beyond doubt.

Scientists from the Institute of Cancer Research carried out genetic tests on the blood of an 11 month old Japanese girl with leukaemia. Her 28 year old mother had died months after birth of the same type of disease.

DNA analysis of blood from both mother and child showed that the cancer cells from both adult and child shared identical genetic mutations.

Further tests carried out on blood samples which had been taken from the newborn baby revealed it had the cancer cells at birth.

However, further genetic testing found the cancer cells were missing a region of DNA which usually allows the immune system to identify cells from another person. Without this, the cancer cells were "invisible" and passed unnoticed by the baby's natural defence mechanisms.

Professor Mel Greaves, who led the study, said: "It appears that in this 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 immune system.

"But 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 is remote."

The research is published in this months Proceedings of the National Academy of Sciences.