Women who have IVF treatment early in adulthood are at greater risk of developing breast cancer, new research suggests.
According to a new Australian study, published in the journal, Fertility and Sterility, women who went through the IVF procedure around their 24th birthday were found to have a 56 per cent greater chance of developing breast cancer than those in the same age group who went through treatments without IVF.
The researchers said: 'For younger women there is some cause for concern, because it appears that they may face an increased risk of breast cancer after IVF treatment.'
The findings were based on a study of more than 21,000 women.
Study author Louise Stewart from the University of Western Australia said younger women might see an increased risk of breast cancer because they are exposed to higher levels of circulating estrogen during their cycles of IVF treatment, according to the Daily Mail.
But there was no increased risk for women who started fertility treatments when they were about 40 years old, regardless of whether they had IVF or not, according to the Australian study
The researchers collected information on 21,025 women between the ages of 20 and 40 who went through fertility treatment at the hospitals of Western Australia between 1983 and 2002.
They were able to piece together enough data to follow the women for some 16 years to see if they developed breast cancer.
Roughly 1.7 per cent of the 13,644 women who only used fertility drugs without IVF ended up developing breast cancer by the end of the study.
That figure was about two percent for women who used fertility drugs and underwent IVF - a difference that researchers said wasn't statistically significant.
This changed when women were divided into different age groups, with women aged 24 about one-and-a-half times more likely to develop breast cancer if they had IVF alongside other fertility treatments.
However, Stewart said they couldn't yet say that IVF was causing the increased cancer risk in younger women, as these women could be different in some significant way from those who only have other types of fertility treatment.
'If for example, younger women who had IVF were more likely to have a specific cause of infertility, and this was related to an increased risk of breast cancer, then it would appear that IVF was related to breast cancer when in fact it was the type of infertility that was more common in women who had IVF,' she said.
Linda Giudice, president-elect of the American Society of Reproductive Medicine, added: 'The development of breast cancer is linked to estrogen exposure and the longer one is exposed, the greater the risk.
'In an IVF cycle there is a short, but significant elevation in circulating estrogen, and whether this is linked to the observations found in the study is not clear at this time.'
Last month, members of the UK parliament are demanded a Government inquiry into the safety of the most popular form of IVF after it was reports linked it with a higher risk of birth defects.
More than 20,000 couples in Britain last year used the intracytoplasmic sperm injection (ICSI) procedure.
But another Australian study, which examined 300,000 births, found that babies conceived using the procedure were twice as likely as babies conceived naturally to have a birth defect.
In response, Conservative MP Dr Dan Poulter, a former obstetrician and gynaecologist and member of the cross-party House of Commons Health Select Committee says there needs to be an investigation into ICSI.
The move could force the UK's fertility regulator, the Human Fertilisation and Embryology Authority (HFEA), to examine its extensive database on ICSI treatments in the UK for evidence to support restricting its use.