That's what I meant; I didn't mean to say it had to be the same cancer. If the breast cancer was located in the same breast and same area that was irradiated (a

That's what I meant; I didn't mean to say it had to be the same cancer. If the breast cancer was located in the same breast and same area that was irradiated (assuming the radiation was local and not systemic), that would make a strong argument that it was likely secondary to the childhood treatment. The fact that the second cancer was breast cancer isn't all that convincing by itself, because it's an all-around common cancer. My point was that it's another explanation that has to be considered. It doesn't mean the explanation you proposed could not be valid.