New research shows that women who have fertility problems are 18 percent more likely to develop ovarian and endometrial or womb cancers in later life.
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Around 2 percent of infertile women are diagnosed with cancers, the researcher authors from Stanford University explain. The study, which is entitled "Risk of cancer in infertile women: analysis of US claims data” was published in the latest issue of the journal Human Reproduction.
The researchers explain that women with fertility problems who undergo In Vitro Fertilization (IVF) are exposed to medications and drugs which alter their hormonal levels and balance. Such hormonal changes could lead to cancer. Infertility is also be linked to genetic problems, the researchers explain, which may increase the likelihood of mutations and cancer.
The team followed more than64,000 women with fertility problems over four years. These women were compared with 3.1 million women who had no fertility problems.
Those who were infertile were more likely to develop cancer. During the study, around 2 percent of the infertile women were diagnosed with cancer, compared to 1.7 percent for fertile women.
We do not know the causes of the increase in cancer that we found in this study - whether it might be the infertility itself, the causes of the infertility, or the infertility treatment. We can only show there is an association between them.
In the future, we hope that we will be able to understand why infertile women are at higher risk of cancer, for example, by identifying a common, underlying mechanism that can cause cancer and infertility.”
Dr Gayathree Murugappan, Stanford University School of Medicine
The researchers explain that there have been concerns regarding the long-term ill effects of the drugs used in IVF. These generally stimulate the ovaries to produce extra eggs which can then be collected and fertilized in the laboratory to create embryos. Such medications also alter the hormones in the body of the woman which can trigger certain cancers such as those of the ovary, endometrium or uterus and breast.
Authors write that infertile women are 78 percent more likely to be diagnosed with uterine cancer and 64 percent more likely to be diagnosed with ovarian cancer. Infertile women are also 59 percent more likely to get gall bladder cancer, says the study.
The low overall incidence of cancer among these women means that one in 49 infertile women would develop cancer during the follow-up period compared to one in 59 women in the women who were not infertile.
Although the absolute increase in cancer risk among infertile women was small, this increase was seen in only a short period of four years of follow-up. We need to carry out further research with longer follow-up to determine what factors may be influencing the long-term risk of cancer for infertile women,” he said.
Dr Michael Eisenberg, Senior Author
Risk of cancer in infertile women: analysis of US claims data. Human Reproduction. 13th March 2019.