IVF treatment may raise the risk of ovarian cancer in later life

By Lilian Anekwe

BMJ Group News

What do we know already?

Many couples who cannot get pregnant naturally decide to have a treatment called in vitro fertilisation (IVF). This is a high-tech treatment where eggs and sperm are brought together in the laboratory.

Often, women who have IVF treatment take drugs or hormone injections to stimulate their ovaries to produce more eggs. This is called ovarian stimulation. The women’s eggs are then collected to be fertilised in the laboratory. There has been some concern that this may increase the risk of problems in the ovaries, and possibly the risk of ovarian cancer.

Many of the studies into the link between ovarian stimulation, IVF, and ovarian cancer have compared women who have had IVF with women in the general population. But this comparison is not always the best one to make, as women who have difficulty getting pregnant, or those who have never been pregnant, are more likely to have ovarian cancer. So comparing women who have IVF treatment with women who have fertility problems but do not have IVF treatment would tell us more about the risks involved with this type of treatment.

Researchers used a national database of 19,146 women in the Netherlands who had IVF ovarian stimulation as part of IVF treatment between 1983 and 1995. They compared these women with a group of more than 6,006 women who had not been able to get pregnant despite having tried for at least one year, but who did not have IVF treatment. They then compared how many women in each group got ovarian cancer over the next 15 years.

What does the new study say?

There were 77 ovarian cancers recorded overall - 61 in women who had IVF treatment and 16 in women who did not have IVF treatment.

When only those women for whom the researchers had at least ten years of information were included in the analysis, women with fertility problems who had IVF treatment were more than twice as likely to have an ovarian tumour as women who did not have IVF treatment. They were also twice as likely to have borderline ovarian tumours, which are not usually fatal, but which normally require surgery. The risk of invasive tumours - those that spread to healthy parts of the ovary - was not higher than would be expected by chance.

There was no additional risk of ovarian cancer for women who had repeated courses of IVF treatment compared with women who had just one treatment. Women who had been treated with fertility drugs before going on to have IVF treatment did not have a higher risk of a tumour than those who had not.

The researchers calculated that for women who have IVF treatment, the overall risk of a tumour in the ovaries is small. Less than one woman in one hundred - 0.45 percent of women - will get ovarian cancer by the time they reach the age of 55. If the results of this study are true, this risk increases to 0.71 percent for women who have IVF treatment.