IVF Hormonal Treatment Causes Negligible Cancer Risk

A new long-term study of women who used ovary-stimulating hormones for in vitro fertilization (IVF) treatment found no widespread evidence of a higher cancer risk.

Researchers at the University of Illinois in Chicago (UIC; USA) and the US National Cancer Institute (NCI; Bethesda, MD, USA) conducted a retrospective investigation involving 12,193 women treated for infertility between 1965 and 1988 at five US sites. Follow-up lasted until 2010, with evaluation based on questionnaire and linkage to US death and cancer registries. Over the 30 years of follow-up, 749 breast, 119 endometrial (uterine), and 85 ovarian cancers were identified in the 9,892 subjects who were successfully followed.

The results showed that use of clomiphene, which included approximately 40% of the cohort, was not associated with any increased breast cancer risk, except when subjects had used the drug in 12 or more treatment cycles; in those cases clomiphene use was associated with a hazard ratio of invasive breast cancer of 1.69, but was not significantly associated with either endometrial or ovarian cancers, even when multiple exposure cycles were involved.

Only 10% of the cohort had been treated with human menopausal gonadotrophins (hMG) and follicle stimulating hormone (FSH), usually in combination with clomiphene, and there was no association with cancer risk identified, except in those who remained childless. The study was presented at the annual conference of the European Society of Human Reproduction and Embryology (ESHRE), held during June 2014 in Munich (Germany).

“The findings do not support a strong relationship between the use of fertility drugs and breast, uterine, and ovarian cancers. Continued monitoring is needed to see whether any of the newer drugs present any danger,” said study presenter and coauthor Humberto Scoccia, MD, of UCI. “Most of the women who enrolled in the study are still relatively young and these types of cancers tend to show up in later years. It is also likely that the proportion of patients using gonadotrophins for ovarian stimulation, particularly in IVF, increased substantially after the mid-1980s.”

Fertility drugs are known to increase levels of the principal female hormones estradiol and progesterone, both of which have been implicated in the pathogenesis of breast, ovarian, and uterine cancers.

Related Links:
University of Illinois in Chicago
US National Cancer Institute