The use of fertility drugs does not increase a woman's risk of developing ovarian cancer, finds a large study from Danish researchers published on bmj.com today.
During the past three decades there has been considerable debate as to whether use of fertility drugs increases a woman's risk of developing ovarian cancer. Previous studies have given conflicting results and concerns remain, particularly for women who undergo several cycles of treatment or who never succeed in becoming pregnant.
So Allan Jensen and colleagues at the Danish Cancer Society examined the effects of fertility drugs on ovarian cancer risk by using data from the largest cohort of infertile women to date.
The study involved 54,362 women with infertility problems referred to all Danish fertility clinics between 1963 and 1998. 156 of these women had ovarian cancer. After adjusting for several risk factors, the researchers assessed the effects of four groups of fertility drugs over an average period of 16 years.
They found no overall increased risk for ovarian cancer after use of any fertility drug. They also found no increased risk among women who had undergone 10 or more cycles of treatment or among those who did not become pregnant.
Although the authors did observe a statistically significant increase in risk of the most common serious type of ovarian cancer among women who had used the drug clomiphene, they stress that this was probably a chance association.
Our results show no convincing association between the overall risk for ovarian cancer and use of fertility drugs, and are generally reassuring, say the authors. However, they do point out that, as many of the study participants have not yet reached the peak age for ovarian cancer, they will continue to monitor the risk.
In a society where there is more and more female infertility and later age at birth of the first child, the unfavourable effects of fertility drugs should be balanced against the physical and psychological benefits of a pregnancy made possible only by the use of these drugs, they conclude.
These data are reassuring and provide further evidence that use of fertility drugs does not increase a woman's risk of ovarian cancer to any great extent although, small increases in risk cannot be ruled out, warns Penelope Webb of the Queensland Institute of Medical Research, in an accompanying editorial.
Some women who take fertility drugs will inevitably develop ovarian cancer by chance alone, she writes, but the current evidence suggests that women who use these drugs are not increasing their risk of developing this highly fatal cancer.