Mammography helps doctors detect breast cancer, but could it cause it? Scientists from the Netherlands suggest that for high-risk women, the answer might be yes.

According to a presentation delivered on Tuesday at the annual meeting of the Radiological Society of North America (RSNA), mammograms can more than double the risk for breast cancer in at-risk women, that is, women who carry a genetic mutation, such as the BRAC1 or BRAC2 genes which drastically increase the chances a woman could develop the cancer, or those who have immediate family members, such as a mother or sister, with the disease.

The study was conducted by gathering together the results from six earlier studies, the only appropriate ones they could find, assessing the effect of low-dose radiation exposure on breast cancer risk among at-risk women.

"We pooled these studies together, and we found that high-risk women who were exposed before the age of 20, or high-risk women who were exposed more frequently were at 2.5 times the increased risk of getting breast cancer," Marijke C. Jansen-van der Weide, Ph.D., epidemiologist at the University Medical Center Groningen in the Netherlands and lead author of the study, tells DOTmed News.

For the study, the average number of mammograms needed to boost the risk of breast cancer in the at-risk population was five.

"So if you are screened every year from 25 to 30, then you already have five exposures," says Jansen-van der Weide.

Weighing risks

Although the review only looked at a small number of earlier studies, Jansen-van der Weide believes there's still enough evidence to say that "something's going on."

"We do not actually know the exact effect of the radiation," she says, "but I think [it's] there."

Though she thinks a clinical study would be forbidden on ethical grounds -- as it would mean knowingly exposing some women to an increased risk for breast cancer -- she recommends a prospective study involving more patients. Of course, the prospective study, which would track at-risk women to see if frequent, early mammograms boosted breast cancer risk, has a major drawback: by the time the results were known, safer imaging modalities might already be perfected. "The problem with radiation is you need 10 to 15 years for the effects to become visible," says Jansen-van der Weide. "So you need a long time."

Careful with screenings before 30

As for patients, Jansen-van der Weide says, "For high risk women, it's very important to be screened, that's the main thing. The second thing is, what should we do?"

"In general," she concludes, "you can say to be careful with mammography screening before 30."

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