Fertility drugs are not linked to an increased risk of breast cancer, a longterm study found.
About 10,000 women who received the drugs, meant to stimulate ovulation, exhibited the same risk of breast cancer during 30 years of follow-up than those who never used the drugs, researchers report.
Previous studies have voiced concerns that fertility treatment, which exposes women to high levels of estrogen, can increase their risk of breast cancer.
"The other worry is that (these drugs) cause increased ovulation and . . . that could be linked to an increase in breast cancer risk," lead author Louise Brinton told Reuters Health.
But Brinton assures readers that this preconceived notion is false.
Out of the 9,892 U.S. women followed over the 30-year period who were potentially infertile, 749 of them were diagnosed with breast cancer. About 38 percent of the study participants were exposed to the fertility drug clomiphene and about 10 percent were exposed to drugs known as gonadotropins.
Fertility drug exposure posed as equal a risk for women compared to those who didn't use the medications to stimulate ovulation.
"It's reassuring that if women desire pregnancy and unfortunately have infertility that they can undergo treatment without modification of their overall risk for cancer later," said Dr. Kurt Barnhart, president of the Society for Reproductive Endocrinology and Infertility.
Researchers note that there was an increased risk of breast cancer among a small subset of women who were prescribed the highest doses of clomiphene. However, current practice limits treatment with this drug to just three to six cycles. Those who received 12 or more cycles increased their breast cancer odds by 70 percent.
"We'll be looking at other results as they emerge and keeping our eye on IVF (in vitro fertilization), which is the more common treatment nowadays," Brinton said.
These findings do not dictate that women should alter how they are screened for cancer in any way, Brinton and her team add.
