Does Timing of Hormone Therapy Affect Breast Cancer Risk?
Initiating hormone replacement therapy before or shortly after the onset of menopause is associated with a greater risk of developing breast cancer compared to those women who started hormone therapy after living with menopause for a few years or more. That's according to (ungated) "Breast Cancer Risk in Relation to Interval Between Menopause and Starting Hormone Therapy".
Other findings include: (1) further confirmation of the observation that hormone therapy increases both false positives and false negatives on mammography; (2) obesity increases the risk of breast cancer in women not on hormone therapy though it has no effect on the risk of those undergoing hormone replacement therapy; (3) contrary to other observations, in this Million Woman cohort risks did not revert to background following cessation of therapy indicating that hormone therapy may not merely "fuel the fire" but may in some cases start it as well; and, (4) the highest risk of breast cancer was seen in women currently on estrogen-progestin who had begun the therapy less than 5 years after the onset of menopause.
