June 4 Wall Street Journal print edition page A5.
"Women who were exposed to chest radiation to treat cancer during childhood have a risk of developing breast cancer as adults that is comparable to that of women with a high genetic risk of the disease, according to a study being presented Monday."
Majia here: See my post yesterday on the bystander and delayed effects for an account of how radiation exposure causes cancer.
It is important to note that these women were exposed to very high levels of radiation. 10 grays is equivalent to 10 sieverts according to the online dose calculator here: http://online.unitconverterpro.com/unit-conversion/convert-group/convert.php?cat=radiation---dose-equivalent
If someone was exposed to 10 sieverts an hour, at one time, it would kill them.