The major cause for the sudden decline seems to be tied to the news on hormone replacement therapy, and the sudden decline in menopausal women using the hormones.
I read that theory yesterday, and it makes no sense. If hormone therapy shrinks the size of tumors and the tumors then go undetected, it would seem that eliminating hormone therapy would cause the tumors to stay the same size or grow and MORE breast cancer would be detected. Or did I misread? I don't know if I read about this on FR or via drudge.
Correlation does not prove causation. My pet theory is that there was a time a few decades back when breast feeding became less popular, especially in the Northeast, For the past decade or so, these bottle feeders have been reaching the age where this cancer is more common. Relatively speaking, breast feeding has only in the last decade or so become more popular again and these women are now reaching the age of higher risk. This would also explain why breast cancer was never so common down south as in the northeast, since us poor southern women kept up that silly backwards habit of breastfeeding, even while 'sophisticated' northern women were bottle feeding.