Hormone therapy in the menopause and breast cancer risk--a review.

OBJECTIVES

To evaluate the association between use of hormones in the menopause and breast cancer risk.

METHODS

A qualitative review of reports published between 1970 and 1995.

RESULTS

The risk of breast cancer starts to increase after 5 or more years of hormone use and remains elevated while taking hormones. Use for 10 or more years may be associated with a 30-80% increase in risk. From 2 to 5 years after stopping taking hormones, the risk seems to return to unity. There is no difference in risk between different types of oestrogens and the addition of progestins does not lower the risk.

CONCLUSIONS

Short term use (less than 5 years) seems safe with respect to breast cancer risk, while longer durations of use may be associated with a small, but significant increase in risk.