Conventional fertility hormones do not increase the risk of breast cancer, gynecological cancers -
"Generally reassuring" the results of an extensive 30-year follow-up study of women treated for infertility
There is "little evidence" that the use of conventional fertility hormones used for ovarian stimulation in the treatment of infertility increases the long-term risk of cancer breast and gynecological, according to the results of a major next 30 years up study. However, prolonged use of clomiphene citrate was associated with a higher risk of breast cancer among women who had used fertility drug for 12 cycles or more. Gonadotropin, commonly used for ovarian stimulation today, were generally not associated with increased risk, except in a subgroup of women who remained childless after treatment.
the results of the study, which was partly funded by the National Institutes of Health in the US, are being presented today at the annual meeting of ESHRE by Dr Humberto Scoccia University of Illinois at Chicago, USA. Dr. Louise Brinton of the National Institute of US cancer was the principal investigator.
The study was a retrospective survey of 12.193 women treated for infertility between 1965 and 1988 in five US sites. Followed lasted until 2010, with an evaluation based on questionnaire and link with death registers and the US cancer. A total of 9892 women were followed for successful outcomes of cancer.
As background to the study, Dr. Scoccia explained that fertility drugs are known to increase the levels of the main female hormones estradiol and progesterone, both of which have been involved in pathogenesis of breast, ovary and uterus. Drugs to stimulate the ovaries to ovulation induction and in vitro fertilization and included clomiphene fertility hormones derived from human subjects - human gonadotropins of menopause, hMG and follicle stimulating hormone, FSH. Both FSH and hMG are not introduced into widespread use until the early 1980s -. And previously clomiphene was the agent most commonly used
"Despite the biological plausibility, the results of studies fertility drugs and breast and gynecological present a mixed picture, some showing increased risk of further declines, and others show no significant association, "said Dr. Scoccia. "However, most of these studies have been a small number of relatively short follow-up periods, and were unable to control other cancer predictors. - Including the indications for the use of drugs, such as anovulation or endometriosis, which could independently affect the risk of cancer many questions remain unanswered. "
in the 30 years of monitoring 749 breast, 119 endometrial (uterus) and 85 ovarian cancers were identified in the 9892 subjects. The "never use" clomiphene - which included about 40% of the cohort - was not associated with an increased risk of breast cancer, except when the subjects had used the drug in 12 or more treatment cycles. In this case the use of clomiphene has been associated with a significant risk ratio of invasive breast cancer of 1.69 (95% CI 1.16 to 2.45). This risk was relatively unchanged after adjustment for causes of infertility and multiple predictors of breast cancer. use of clomiphene was not significantly associated with either of the endometrium (HR 1.41, 95% CI 0.98 to 2.04) or ovarian cancer (HR 1.34, IC 95% from 0.86 to 2.07) cancers, even when several cycles of exposure were involved.
Only 10% of the cohort was treated with gonadotropins (hMG and FSH) - usually in combination with clomiphene - and there was no association with the risk of cancer identified, except those remained childless (HR 1.98; 95% CI, 1.04.60). "Given that the majority of our women who received gonadotrophin also received clomiphene," said Dr. Scoccia, "it is likely that the increased risk among nulliparous women reflects an effect on their risk of infertility rather than of drug use. "
by further comments, he said that the study results do not support" a strong relationship "between use of fertility drugs (mainly of clomiphene citrate) and breast, uterine and ovarian cancer. He described the results as "reassuring in general," noting that this study had a much more statistical power than previous efforts. despite the long-term follow-up study, he urged continued monitoring due to the 'relatively young age of our study population and the subsequent peak incidence of most of these cancers. " It is also likely that the proportion of patients using gonadotropins for ovarian stimulation - especially in IVF. - A significantly increased after the mid-1980s
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