Cancers after ovarian stimulation

Dear Professor Winston,

I have been trying to find out information on the increased risk of cancers in women having IVF treatment/fertility injections. I believe the risk is mainly around ovarian cancer. I understand from your book that there is no clear evidence of an increased risk of ovarian cancer in women who are successful with treatment in comparison to women who are infertile but there is some doubt about those who are given these drugs but do not become pregnant. Do you happen to know how big the increased risk is for this latter group i.e. those who are unsuccessful following treatment (for example in % terms)? And is there a particular piece of research I can be referred to?

Many thanks, once again.

Kind regards,


Dear A.,

There is a wealth of information about the risk of ovarian cancer after ovarian stimulation now collected over more than 35 years.

The best paper on the subject I can refer you to in recent years is from the Cochrane database, which collates published information from many studies and follow-ups.  The most recent study of this kind published in 2013 by Rizzuto et al (Cochrane Database of Systematic Reviews 2013, Issue 8. Art. No.: CD008215. DOI: 10.1002/14651858.CD008215.pub2.), looked at carefully collected data from 25 different studies of a total of 182,972 women.  The bottom line from these data suggest there is no convincing evidence that fertility drug treatment increases the chances of invasive ovarian cancer.  There may be an added risk of so-called “borderline ovarian cancers” in women who are infertile but who don’t get pregnant, but there is no evidence that this risk is affected by the use of fertility drugs.  Women who are infertile have a slightly increased risk of ovarian cancer anyway.

There are two other cancers which are important.  Firstly, with regard to breast cancer, a large study from the Low Countries of around 25,000 women showed no clear evidence of an increased risk of breast cancer beyond that found in a normal group of women in the general population. This study (JAMA. 2016;316(3):300-312. doi:10.1001/jama.2016.9389.), just published in the journal of the American Medical Association was published in July by van den Belt-Dusebout and numerous colleagues.

The other cancer where there has been a suggestion of increase risk is the incidence of bowel cancer.  Dr Spaan and colleagues (May 2016; Clin Gastroenterol Hepatic 14: 729-737) from the Netherlands published data on 19,158 undergoing IVF and another group of 6,000 women having fertility treatment without IVF. The news is good as there appeared to be no evidence that the risk of colon or rectal cancer was increased irrespective of how long the treatment with fertility drugs was used.

I hope that this information is reassuring.

Best wishes

Robert Winston