Rad risks in young breasts.

Rad risks in young breasts

An apparent lack of breast cancers in women who as infants survived the bombing of Hiroshima and Nagasaki long suggested that young breast tissue was somehow protected from ionizing radiation's carcinogenic effects. But a recent increase in breast cancers among these women has hinted the problem only reveals itself slowly. Now a study of 1,201 U.S. women who as infants received x-ray treatments to shrink enlarged thymus glands confirms this grim view, revealing a 3.5-fold increased risk of breast cancer among these women compared with their nonirradiated sisters after an average of 36 years. The new figures indicate that the younger the breast tissue, the greater its susceptibility to x-ray's ill effects.

While physicians no longer treat enlarged thymuses with radiation, the findings call for "judicious" exposure of young breast tissue to any diagnostic or therapeutic radiation, says study coauthor Nancy G. Hildreth of the University of Rochester (N.Y.) School of Medicine and Dentistry.

A study led by Anthony B. Miller of the National Cancer Institute of Canada in Toronto also finds a decreased sensitivity of older breast tissue to the effects of ionizing radiation. Miller concludes that if mammography provides even a small increase in the detection of early breast cancers, this benefit would outweigh any radiation risk associated with the low-dose procedure. Both studies appear in the Nov. 9 NEW ENGLAND JOURNAL OF MEDICINE.