IVF link to breast cancer dispelled

Study encouraging, but experts call for more research

Women who undergo in vitro fertilization to have a baby have enough to worry about without fretting about a possible increase in their risk for breast cancer. Last week they got good news: The biggest study of its kind found IVF didn’t increase women’s chances of developing the disease.

And that was just the latest bit of reassurance about the connection — or lack of one — between cancer and IVF.

In recent years, some of the same Dutch scientists involved in the breast cancer study have released research suggesting that women who undergo IVF aren’t more likely than the general population to develop colon or endometrial cancer.

As in many complicated medical issues, experts say, more research is needed, especially on the topic of IVF and ovarian cancer. Last fall, British researchers published a large study that found that women who undergo IVF are over a third more likely to develop ovarian cancer than those who don’t get the treatment.

At the time, those researchers cautioned that the connection might be partly caused by the patients’ underlying infertility — which is itself is a risk factor for ovarian cancer — rather than the treatment itself. And many scientists agree with that.

“I don’t think there is a direct link between IVF and ovarian cancer,” said Terri Woodard, assistant professor in the Department of Gynecologic Oncology and Reproductive Medicine at MD Anderson Cancer Center. “There are many things that confuse the issue.”

Mia Gaudet, the strategic director of breast and gynecologic cancer research at the American Cancer Society, said the ovarian-cancer issue remains “an open question.”

Questions have swirled around IVF for decades because the treatment regimens require elevating certain hormones to levels far above normal, and some of those hormones are known to affect cancers. For years, studies have come down on one side, then the other, on whether IVF is linked to breast cancer.

The new study was published July 19 in the Journal of the American Medical Association and was conducted by researchers at the Netherlands Cancer Institute. It involved more than 25,000womenwith a median follow-up of more than 20 years.

“Iwas very excited about it,” Woodard said. She said her patients ask her whether their breast-cancer risk will rise, and now “we have a general, population-wide answer that says, no, we don’t think so.”

Gaudet, in assessing the breast cancer study, was encouraged but cautious. “This is a very reassuring first step,” she said. “But it’s not conclusive.” For one thing, she said, the medications and treatment protocols have changed over the years, and so the risks might have changed aswell.