When E! News anchor Giuliana Rancic announced she discovered she had breast cancer during her IVF treatments, many women also going through such treatment likely wondered if they were at greater risk of the disease. Experts seem to agree that generally the answer is no.

But Dr. Kala Visvanathan, an associate professor of oncology and epidemiology at Johns Hopkins, says more study is needed on women in certain subgroups such as older women and those with higher risk factors for breast cancer.

Much of the published data involve younger women using certain hormones and other fertility drugs, and the age of women in treatment and their medications have changed somewhat over time.

The numbers using the technology certainly has grown in the last few decades: There were more than 60,000 live births from IVF cycles in 2009, according to the U.S. Centers for Disease Control and Prevention, or more than 1 percent of all infants born in the United States.

“The data so far doesn’t suggest that there is a link when you look at it overall,” she said. “Whether there is a link between subgroups of individuals is yet to be known.”

Women who are older may want to talk to their doctors about whether a mammogram is a good idea for them before they begin IVF, Visvanathan said. Age is a risk factor for breast cancer, as is delaying childbirth. Also, whatever is causing the infertility may also put women at higher risk for cancer.

Rancic, 36, who is a University of Maryland, College Park alumna, told the Today show that she had a mammogram on her doctor’s advice. She said her doctor told her, “'I don't care if you're 26 or 36, but I will not get you pregnant if possibly there's a small risk that you have cancer because the hormones will accelerate the cancer. I never in my wildest dreams expected anything would be wrong.”

Visvanathan said there isn’t good data on whether the estrogen used in IVF can exacerbate cancer that already is forming from abnormal cells in the breast. Estrogen generally is known to fuel tumors. And estrogen used for long periods of time in hormone replacement therapy in post-menopausal women is also known to cause cancer.

“The good news is the data doesn’t show a large association between IVF and breast cancer,” Visvanathan said. “There’s not data to say you shouldn’t do this. But you do need to balance that with your risk.”