X-rays raise breast cancer risk in some women: study

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) – X-rays may greatly raise the risk of
breast cancer in women who are genetically susceptible to the
disease, researchers reported on Monday.

A study of women with genetic mutations known to cause
breast cancer showed that having a chest X-ray could double or
even triple that risk.

The findings are not clear-cut and not clear what kind of
chest X-rays pose the greater risk, said Dr. David Goldgar of
the University of Utah School of Medicine, who helped lead the
research.

The researchers looked only at women who have a certain
version of the BRCA1 and BRCA2 breast cancer genes, known to
raise the risk of both ovarian and breast cancer.

“The results from this study raise potentially significant
clinical considerations,” the researchers wrote in a report,
published in the Journal of Clinical Oncology. “The absolute
risk of breast cancer by age 50 years is in the order of 40
percent in BRCA1 carriers and 15 percent in BRCA2 carriers.”

The team focused on 1,600 women, who were asked whether
they had ever had a chest X-ray, if it was before age 20, and
how many they had been exposed to.

Women with mutations in BRCA1 or BRCA2 who reported having
a chest X-ray were 54 percent more likely to develop breast
cancer than those who had never had one, the study found.

Women exposed to X-rays before age 20 had a 2.5-fold
increased risk of developing breast cancer before age 40,
compared with those who had never had a chest X-ray.

“Since BRCA proteins are integral in repairing damage to
breast cells, we hypothesized that women with BRCA 1/2
mutations would be less able to repair damage caused to DNA by
ionizing radiation,” Goldgar said.

Mammograms were specifically excluded from the study.

“Typically, the main reason I would think that most of the
people in our study would have had X-rays was for screening to
tuberculosis before going to school or sometimes a job
requirement,” Goldgar said in a telephone interview.

“If my daughter was 30 and known to be a (BRCA1 or BRCA2)
carrier I wouldn’t say ‘don’t have a mammography.”‘

Now the team is trying to get more precise details from the
women on what kinds of X-rays they had and when.

“It seems from our study and from other studies that
younger age exposure is important,” Goldgar said.