Pregnant women with breast cancer can be safely treated with a common chemotherapy combination during both the second and third trimesters, researchers report.

The majority of babies will not experience significant short-term complications linked to maternal treatment, they added.

“Further follow-up of the children is required to determine the potential long-term effects of this exposure,” wrote researchers at the M.D. Anderson Cancer Center, in Houston. “However, our short-term data are reassuring.”

The study was published in the Aug. 7 online edition of Cancer.

As women have babies later in life, experts have hypothesized that more women will be diagnosed with breast cancer while they are pregnant. However, there’s little data on how chemotherapy might affect a child in utero.

To help answer that question, the Texas team undertook a trial involving 57 pregnant breast cancer patients. All were treated with a common chemotherapy protocol (FAC or 5-fluorouracil, doxorubicin, cyclophosphamide) either after surgery or before surgery. More than one-third (35.1 percent) of the women underwent surgery in their second trimester, while 33.3 percent had surgery after delivery. Most of the women were diagnosed with advanced-stage breast cancer.

Of the original group of women, 40 are now alive and disease-free, three have had recurrences of breast cancer, 12 died of the disease, one died of other causes and one was lost to follow-up.

All women who delivered had live births; there were no stillbirths or miscarriages. One child had Down syndrome, and two had congenital abnormalities including club foot. The researchers followed the children’s health for more than three years and found that most of the children were healthy although two had special education needs. Some of the children had breathing difficulties requiring ventilation at the time of birth.

TENS of thousands of women whose mothers took an anti-miscarriage drug are nearly twice as likely to develop breast cancer, researchers have warned.

A form of synthetic oestrogen called DES - diethylstilbestrol - was routinely given to pregnant women from the 1940s, as it was said to cut the risk of miscarriage and help produce healthy babies.

It was withdrawn in the 1970s amid mounting health concerns, and a new study of more than 6,000 women in the United States by academics at Boston University has found those now over 40 who were exposed to the drug in the womb are 90 per cent more likely to get breast cancer.

There was some evidence that those over 50 had treble the normal risk, but scientists said the study had not included enough people in that age group to be confident about the figure.

It was already known that so-called “DES-daughters” were at a greater risk of a rare form of vaginal cancer and suffered from fertility problems, including an increased chance of miscarriage. Men can also be affected.

About 200,000 women in the UK are thought to have taken DES, but it is unclear how many of their children are affected - many may have no idea their mothers took the drug.

The Boston team, in a report in the journal Cancer Epidemiology, Biomarkers and Prevention, said those affected should avoid hormone replacement therapy, due to the greater cancer risk.

Jane Kevan, of the campaign group DES Action, said the study confirmed the results of a smaller survey in 2002 that first suggested a link with breast cancer. She said: “The reaction from most of us in the group is, it’s another thing to worry about. Where is it all going to end?”

Heather Justice, 53, whose mother took DES for five weeks, developed vaginal cancer when she was 25 and is worried about the prospect of breast cancer.

“It was known to be carcinogenic in the 1930s and 1940s and should never have been given out. We’ve known since the 1970s about the risk of vaginal cancer and now, as these women are getting to the menopause and there are hormonal changes, we are seeing breast cancers starting to emerge,” she said.

Dr Sarah Rawlings, of Breakthrough Breast Cancer, said: “The link between women who took DES during pregnancy and their daughters potentially having a higher risk of breast cancer is very concerning. If women are worried, we would advise them to speak to their doctor.”