Radiation Exposure

From Annual Mammography

Increases Breast Cancer Risk in Young High-Risk Women

Fran Lowry  

(eMedicine Clinical Reference Magnetic Resonance Mammography)

December 2, 2009 (Chicago, Illinois) — The low doses of radiation associated with annual screening mammography could be placing high-risk women in even more jeopardy of developing breast cancer, particularly if they start screening at a young age or have frequent exposure, according to new research presented here at the Radiolo-gical  Society of North America 95th Scientific Assembly and Annual Meeting.

A meta-analysis of 6 studies found that women with BRCA1 or BCRA2 gene mutations or a family history of breast cancer who were exposed to radiation, either from mammography or chest x-rays, before the age of 20 had a risk for breast cancer that was 2.5 times higher than their counterparts who were not exposed to radiation (95% confidence interval [CI], 1.9 - 3.2).

The analysis, which examined 9420 high-risk women, also found that 5 or more mammograms increased risk 2.5-fold (95% CI, 1.6 - 3.9), Marijke C. Jansen-van der Weide, PhD, from the University Medical Center Groningen in the Netherlands, reported.

Overall, exposure to low-dose radiation increased breast cancer risk by a nonsignificant 1.5 times, compared with no exposure, Dr. Jansen-van der Weide said.

The mean age of the women in the analysis was 45 years. The cumu-lative dose of radiation they received ranged from 0.3 to 24 mSv.

"The take-home message here is that high-risk women who are younger should be careful about mammography screening," she told Medscape Radiology. "Because they are young, they also have dense breasts, which poses a problem with mammo-graphy. They should explore alternative screening methods."

The average woman has a 10% chance of developing breast cancer during her lifetime. In comparison, women who are carriers of the BRCA1 gene mutation have a 57% chance, and BRCA2 carriers have a 49% chance of developing breast cancer. Screening these women must start at an early age, since many will get breast cancer in their 30s or 40s, Dr. Jansen-van der Weide said.

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