By Kate Kelland
STOCKHOLM (Reuters) - Treating pregnant cancer patients with powerful chemotherapy drugs appears not to harm their unborn children, but pre-term delivery to avoid subjecting them to chemotherapy does, according to a study by cancer experts on Tuesday.
Scientists who studied the health and mental development of children born to mothers treated for cancer in pregnancy found they were not affected by chemotherapy, but were harmed if they were born prematurely, either naturally or by induction.
"The data suggest the children suffer more from prematurity than from prenatal chemotherapy," said Dr. Frederic Amant, a gynecological oncologist at the University Hospitals Leuven in Belgium, who led the research and presented his findings at the European Multidisciplinary Cancer Congress (EMCC) in Stockholm.
While results presented at meetings are usually considered preliminary, he said the data show there is no need for pregnant cancer patients to have abortions or delay chemotherapy treatment beyond the first trimester, but stressed that doctors should avoid inducing early birth if at all possible.
An estimated 2,500 to 5,000 pregnant women in Europe are diagnosed with cancer each year -- a diagnosis that is doubly traumatic as mothers-to-be worry that either the disease or the treatment could harm their unborn child.
Amant said that in his experience, many women decide to have an abortion because they are unaware of the cancer treatment risks to the fetus, but assume it is likely to be harmful.
Doctors, too, often advise women to either delay their cancer treatment or induce delivery of the baby early -- generally at around 32 weeks gestation, he said.
But according to his findings, that advice is misplaced if chemotherapy is given after the first 12 to 14 weeks of pregnancy. Only a fraction of the chemotherapy passes through the placenta and gets into the fetus, Amant said, and the drugs appear to have no health impacts on the babies' development.
Among the 70 children born from 68 pregnancies in the study, around two-thirds were delivered before 37 weeks gestation.
Amant's team found the rates and types of congenital defects among the babies were similar to the general population, as was growth, general health and development. The researchers also found no heart abnormalities.
But they found that while cognitive development -- measured by scores such as intelligence quotient (IQ) and behavioral tests -- was in the normal range for most of the children, those that had below-normal IQs were mainly those born prematurely.
It is already well known that babies born very early have a higher risk of developing learning difficulties, and recent studies have also shown that children born even 1 or 2 weeks before their 40-week gestation due date are also more likely to develop learning difficulties.
Amant said that because the number of women in this study was small and the follow-up time was relatively short, his team plan to study larger numbers for longer in future research.
"At this stage we do not know the full, long-term consequences of prenatal chemotherapy, including its effect on the children's fertility and likelihood of developing cancers when they are older," he said.