Hormone therapy near the start of menopause may increase breast cancer risks

New studies may show that starting hormone therapy near the start of menopause may increase breast cancer risks more than if hormone replacement therapy takes place some time after menopause.

For the study, researchers found that women starting hormone therapy five years or more after menopause noticed no breast cancer risk increases. Typical risk factors, like obesity, type of therapy, and duration of therapy, did not seem to have any affect on the risks either.

Oxford University researchers analyzed data from the Million Women Study (MWS).

Making some assumptions about risk factors and potential previous hormone therapy users, researchers analyzed data on more than one million women. Additional analysis took place on the type of therapy used.

What the study found was that women who began hormone replacement therapy near the start of menopause noticed higher breast cancer risks when compared to women who waited five years or more to start therapy.

Researchers explain that the interval period between the onset of menopause and start of hormone therapy significantly affect breast cancer risks.

The entire study can be found in the National Cancer Institute journal.