Diagnostic radiation exposure to the chest at young ages may increase risk of breast cancer in BRCA1/2 mutation carriers

Women carrying a mutation in the BRCA1- or BRCA2- genes (which control the suppression of breast and ovarian cancer) who have undergone diagnostic radiation to the chest before the age of 30 may be more likely to develop breast cancer than those who carry the gene mutation but who have not been exposed, the Gene-Rad-Risk study published on British Medical Journal today reveals.

This collaborative study, coordinated by the International Agency for Research on Cancer (IARC, Lyon, France), was initiated by Dr. Elisabeth Cardis when she was head of the Radiation Group at IARC, before her move to CREAL (Centre for Research in Environmental Epidemiology) in 2008 as the Coordinator of the Radiation Program.

The results suggest that BRCA1/2 mutation carriers may have a 1.5- to 2-fold increased risk of developing breast cancer when exposed to one or more diagnostic radiation procedures, compared with carriers who were not exposed. This increased risk was observed for diagnostic radiation procedures received before age 30 but not for procedures received later in life. Diagnostic radiation procedures considered included fluoroscopies, X-rays, mammograms, CT scans, and other types like bone scans and nuclear diagnostic procedures.

According to study authors Dr. Anouk Pijpe and Prof. Dr. Flora E. van Leeuwen from the Netherlands Cancer Institute in Amsterdam, this estimate “should be interpreted with caution because there were few women with breast cancer who had had a mammogram before age 30 in the study”.

The authors conclude that “exposure to diagnostic radiation before age 30 was associated with an increased breast cancer risk in BRCA1/2 mutation carriers”. They say however due to “puzzling” findings in the differences between breast cancer risk for BRCA1 and BRCA2 carriers, larger studies are needed to determine whether a difference does in fact exist. In the light of these findings, the authors recommend the use of non-ionizing radiation imaging techniques, such as MRI, for screening in women who are BRCA1/2 mutation carriers.