The study found little association between the use of drugs like Clomid andthe cancer.
There has long been concern that the ovulation-stimulating andovulation-regulating drugs used to treat infertility raise ovarian cancer risk.Several small studies conducted in the 1990s suggested that they do, but morerecent studies failed to show an association.
Now the largest, most rigorously designed trial ever to address the questionshows “no convincing association” between fertility drug use and ovariancancer.
Women in the study were followed for an average of 16 years after treatment.Researchers say longer follow up is needed to rule out a strong link betweenthe fertility drugs they took and ovarian cancer.
Their average age at follow-up was just 47, and the peak age for ovariancancer is the early 60s.
But lead researcher Allan Jensen, PhD, of the Danish Cancer Society, tellsWebMD that the new findings should be viewed as reassuring.
“If there were a strong association we would definitely expect to see it bynow, and we don’t,” he says. “But we will certainly continue to follow thesewomen.”
Fertility Drugs, Ovarian Cancer
Jensen and colleagues reviewed the medical records of 54,362 infertile womentreated at fertility clinics in Denmark between 1963 and 1998. Duringfollow-up, 156 of the women were diagnosed with ovarian cancer.
After adjusting for risk factors associated with the cancer, the researchersexamined the impact of four different fertility drugs on ovarian cancer risk:clomifene citrate (Clomid, Serophene); gonadotropins; human chorionicgonadotropin; and gonadotropin-releasing hormone.
The found no overall increased risk for the cancer related to use of any ofthe fertility drugs.
In addition, no treatment-related increase in risk was seen among women whohad undergone 10 or more treatment cycles and women who never became pregnant— two groups that have been believed to be especially vulnerable.
A small increase in risk for one of the most deadly types of ovarian cancerwas seen in women who took Clomid or Serophene, but Jensen says that this wasprobably a chance association.
The study appears in the latest issue of the journal BMJ OnlineFirst.
Infertility Increases Ovarian Risk
Studying the impact of fertility drugs and ovarian cancer is complicated bythe fact that infertile women and women who’ve never had children already havea higher than average risk for the cancer, says research Penelope Webb, PhD, ofAustralia’s Queensland Institute of Medical Research.
She tells WebMD that one of the greatest strengths of the new study is thatresearchers went to great lengths to control for this.
In an editorial published with the study, Webb writes that the findingsprovide further evidence that fertility drugs have no great impact on ovariancancer risk.
“Some women who take fertility drugs will inevitably develop ovarian cancerby chance alone, but current evidence suggests that women who use these drugsdo not have an increased risk of developing ovarian cancer,” she writes.
Earlier findings by the Danish group involving the same cohort of infertilewomen also suggest no link between fertility drug use and an increased risk forbreast cancer, thyroid cancer, and malignant melanoma, Jensen says.