Women who discover they have breast cancer while they are pregnant can be treated with chemotherapy without endangering the health of their unborn baby, according to research to be presented at the seventh European Breast Cancer Conference (EBCC7) in Barcelona on Friday.

Dr Sibylle Loibl, Assistant Professor in Obstetrics and Gynaecology at the University of Frankfurt, Germany, and a member of the German Breast Group, will tell the conference that pregnant breast cancer patients can be treated as close as possible to standard recommendations because chemotherapy delivered while babies were in the womb did not appear to cause the babies significant problems at or after birth.

"Until now, the evidence upon which we based our decisions about how to treat pregnant women with breast cancer has been largely limited to case studies and retrospective investigations. For this reason doctors have tended to be cautious in their approach to treatment because of fears about the effect it might have on the foetus, even though it meant that women did not necessarily receive the best treatment for their cancer," said Dr Loibl. "Therefore, the German Breast Group set up a registry to collect data both retrospectively and prospectively from patients who have been diagnosed with breast cancer during pregnancy. It is the only international registry to focus on the outcomes of both the mother and the baby."

The researchers entered details of 235 patients prospectively (119) and retrospectively (116) to the registry between April 2003 and October 2009. The ages of the women ranged between 23 and 46 with an average (median) age of 33. Breast cancer was diagnosed, on average, at 23 weeks into the pregnancy. Not all the data are complete yet, but out of 151 women, 91 received an average of two cycles of chemotherapy while they were pregnant.

The average gestational age of the babies at the time of delivery was 36 weeks, ranging between 28 and 42 weeks. Babies that were exposed to chemotherapy during pregnancy were born slightly lighter than babies who were not: an average of 2636mg, compared to 2791mg.

Of the 91 babies exposed to chemotherapy, three were born bald (alopecia), one was small for gestational age, one had trisomia 18 (a chromosomal disorder) and died one week after birth, one had necrotic enterocolitis (a severe bacterial infection of the intestine) and died three weeks after birth, one developed sepsis (blood infection), one developed neutropenia (low white blood cell count) and two had anaemia. Of the 60 babies who were not exposed to chemotherapy, one had temporary apnoea (breathing interruption), one had an increase in C reactive protein (a protein that appears in response to inflammation or infection) and one had gastroenteritis.

Dr Loibl said: "Most of the problems described in the babies exposed to chemotherapy were not related to the treatment but were most probably due to other circumstances (for instance, necrotic enterocolitis due to preterm delivery or trisomia 18). Normally, in nature, there is a risk of malformations of between one and two percent, and other problems such as infection can happen. The foetal outcomes of these babies that received chemotherapy were not significantly different from those who did not.

"Therefore, this study suggests that pregnant breast cancer patients can be treated as close as possible to standard recommendations and receive chemotherapy, if it is indicated, while they are pregnant. Ideally, this should take place in the care of specialised, multidisciplinary teams. We would like to generate more robust data to confirm this and so the registry is continuing and we are updating and completing the data."

In addition to the data on outcomes for mothers and babies, Dr Loibl and her colleagues are also collecting tumour specimens and placenta material from the women who are being followed prospectively, and these are sent to the German Breast Group's biomaterial bank. The researchers hope that this will give them important information in the future about the effects of pregnancy and chemotherapy on outcomes for mothers and babies.

Source: 7th European Breast Cancer Conference

Watch an interview with Dr. Sibylle Loibl on ecancertv here.