Although no firm link between IVF and breast cancer has been established, some boffins are worried about the potential effects of fertility drugs used to stimulate the ovaries so that eggs can be collected and fertilised, reports Times Online.
These expose the body to high levels of oestrogen, a female hormone to which some breast tumours are sensitive.
The research, which was led by Alexandra van den Belt-Dusebout, of the Netherlands Cancer Institute, should reassure women considering fertility treatment that it does not pose a breast cancer risk.
The study was presented at the American Society for Reproductive Medicine conference in San Francisco.
In the study, the Dutch team used a national registry to investigate more than 25,000 women who received IVF or other fertility treatments between 1980 and 1995. Almost 19,000 of the women had had IVF, while the other sub-fertile women had had different treatments or none.
There was no statistically significant difference in breast cancer incidence between either group as a whole and the general population. There was a slight increase in breast cancer risk among the infertility patients who had been followed up for the longest periods - 15 years - but this was accounted for by the size of their families.
The study also compared women who had had different numbers of IVF cycles, and found no relationship between extra cycles and breast cancer risk.