Study: IVF 'may increase breast cancer risk in younger women'

Women who go through in vitro fertilization (IVF) early in life have a higher risk of developing breast cancer compared to women who opt for
other fertility treatments, according to an Australian study.
Women who started taking fertility drugs and went through IVF around their 24th birthday had a 56 per cent greater chance of developing breast cancer compared to those in the same age group who went through fertility treatments without IVF.
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.
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 and published in the journal Fertility and Sterility.
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.
However, she added: 'I don't think it's a huge increased risk that you should worry or panic (about).'
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.'
The researchers said the study results would reassure women who start IVF treatment in their 30s and 40s.
However, they added: 'Women should be aware that delivering their first child late in reproductive life, whether assisted by IVF or not, is associated with an increased risk of breast cancer.'
Statistically, younger women have a greater chance of successfully having a baby following IVF.

They suggested a follow-up study of women who undergo a greater range of cycles to see if there's a connection between IVF 'dose' and breast cancer rate.

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