According to a study published Online First in The Lancet Oncology, babies born to women with breast cancer who received chemotherapy while pregnant do not seem to be at greater risk of complications.

The researchers analyzed over 400 women from across Europe who had been identified as having early-stage breast cancer during pregnancy. 197 women went through chemotherapy while pregnant, additionally the researchers evaluated if their newborns experienced any adverse effects that may be due to the cancer drugs.

While babies whose mothers had gone through chemotherapy during pregnancy had, on average, a lower birth weight than newborns whose mothers had not undergone chemotherapy, the team found other apparent differences amongst the groups. Infants subjected to chemotherapy in utero seemed to not have greater risk of birth defects, no lower Apgar scores, no more frequent blood disorders or alopecia than infants whose mothers did not undergo chemotherapy while being pregnant.

Professor Sibylle Loibl, of the German Breast Group which directed the research, said: “If our findings are confirmed by other studies, breast cancer during pregnancy could be treated as it is in non-pregnant women without putting foetal and maternal outcomes at substantially increased risk.”

The number of chemotherapy cycles the women experienced during pregnancy did not seem to impact the infants’ birth weight, indicating that the lower birth weight is not clinically significant. Professor Loibl, explained:

“In the general population, about 10-15% of infants are born preterm, but in our study, 50% of women with breast cancer delivered preterm, with 23% delivering before the 35th week of gestation. More complications were reported in the group of infants exposed to chemotherapy than in the group not exposed to chemotherapy. However, most complications were reported in babies who were delivered prematurely, irrespective of exposure to chemotherapy.

Our findings emphasise the importance of prioritizing a full-term delivery in women who undergo chemotherapy while pregnant. Illness and mortality in newborn babies is directly related to gestational age at delivery. This is an important clinical message because the decision to deliver the foetus preterm is often taken without medical indication. Our work suggests that treating patients with breast cancer while pregnant is possible, and there is no need to interrupt the pregnancy or receive inferior therapy.”

In a associated Comment, Olivier Mir of the Cancer Associated with Pregnancy Network, France, emphasizes the timeliness of the findings: “The concomitant incidence of breast cancer and pregnancy is rising in high-income countries, because of increases in maternal age at the time of first pregnancy.”

However, Dr Mir highlights that the impact of chemotherapy in expectant mothers is under-researched, and additional research should focus on exactly how chemotherapy doses ought to be worked out for pregnant patients, and longer-term studies ought to evaluate the impact of in utero chemotherapy on children as they get older: “Very few studies have assessed the long-term outcomes of chemotherapy during pregnancy, and further work is needed to determine whether the foetal risks outlined by Professor Loibl and her colleagues could be minimized with optimal drug selection and dosing.”

Written by Grace Rattue