Pregnancy is safe for women after breast cancer – and may even have a protective effect
Pregnancy boosts oestrogen levels but did not trigger cancer's return
10:19 GMT, 21 March 2012
Breast cancer sufferers in remission have been told for the first time it is safe for them to become pregnant.
Previously doctors have feared that pregnancy can boost levels of oestrogen in the body and cause the most common form of the cancer to return.
Baby joy: Women in remission who become pregnant appear to survive longer than those who do not
However, the new findings, presented at the European Breast Cancer Conference in Vienna, suggest it is safe for women to fall pregnant even within the first two years after diagnosis.
Furthermore, the study found that patients who become pregnant appear to survive longer than those who do not, although further research is needed in this area.
Oestrogen is a female sex hormone which stimulates some breast cancers to grow by triggering particular proteins (receptors) in cancer cells.
In a previous study, Dr Hatem Azim Jr and colleagues performed a review of 14 trials which showed it was safe for breast cancer patients to conceive.
However, the study was unable to show whether this was the case for women with oestrogen receptor positive (also known as ER+) disease.
In the new research, Dr Azim, a medical oncologist at the Jules Bordet Institute in Brussels, and colleagues, enrolled 333 women whose oestrogen receptor status (positive or negative) and disease outcome were known.
They had become pregnant at any time following diagnosis and were in remission at the time they conceived.
The group was matched with 874 similar breast cancer patients who did not become pregnant, and who acted as controls.
Over a period of almost five years following pregnancy, 30 per cent of all women in the study saw their disease come back.
Dr Azim said: 'Out of all the women, 57 per cent had ER+ disease, but the study showed there was no difference in the length of time women with either ER+ or ER negative (ER-) disease survived without their disease recurring compared with those who did not become pregnant.'
He said a second finding, that patients who became pregnant within two years of breast cancer diagnosis appeared to have a better disease-free survival compared to those who did not become pregnant, should be interpreted with caution.
Neither breastfeeding nor abortion or miscarriage appeared to have an effect on the women's outcome.
Dr Azim added: 'Frequently when women with history of breast cancer become pregnant, some physicians advise them to have an abortion for fear that completing the pregnancy could have a detrimental effect on the outcome of their disease.
'We found that this was not true and the outcome was similar, irrespective of whether the pregnancy was completed or not.'
He said abortion 'should not be promoted for therapeutic reasons in these patients' and said the study shows 'convincingly that pregnancy any time following breast cancer diagnosis is safe, irrespective of ER status'.
The patients in the study had an average age of 34, ranging from 21 to 48 years old.
Professor David Cameron, from the University of Edinburgh and chairman of the conference, said: 'This is an important study, as it can give women much more confidence that a wanted pregnancy after treatment for breast cancer does not necessarily mean a poorer chance of being able to live to bring up children.
'However, it is important to acknowledge that there are limitations in this kind of case control study, and so whilst an important piece of research, it cannot yet be taken as definitive proof that there is no adverse effect of a subsequent pregnancy.'
Woman are advised to check their breasts regularly for any changes
Dr Rachel Greig, senior policy officer at Breakthrough Breast Cancer, said: 'This study may offer reassurance to breast cancer patients who want to have a baby after finishing their treatment.
'It shows that most women who become pregnant after breast cancer are not at increased risk of developing the disease again.
'However, we would always encourage women wishing to have a baby after breast cancer to discuss this with their doctor.'
Grete Brauten-Smith, clinical nurse specialist for younger women at Breast Cancer Care, said: 'We welcome this research which supports previous evidence that becoming pregnant following a breast cancer diagnosis, whether or not you are oestrogen receptor positive, does not increase the risk of recurrence.
'While the study will go some way to easing the concerns of prospective mothers who have had breast cancer, it should be interpreted with a degree of caution.
'Currently, most cancer specialists recommend waiting two years after hospital-based treatment before trying to become pregnant.
'The findings do however reinforce the importance of discussing fertility preservation prior to treatment for breast cancer.'