Influence of HRT on the Incidence of Breast Cancer

Dr. John Collins presented a thorough review of the literature concerning the interaction of hormone replacement and breast cancer entitled "HRT and Breast Cancer: The Evidence and the Issues" with the following general conclusions:

• The cause of the development of breast cancer is a multifactorial event.
• The increased risk with hormonal replacement is similar to that of delayed menopause.
• There are no differences in risk in the types or dosages of hormone used for replacement.

Differences in Risk

The increased risk of each year of hormone replacement therapy (HRT) is 1.023, and the increased risk of each year of delayed menopause is 1.028, thus it appears there is essentially no difference in a year of hormone replacement or a year's delay in experiencing menopause.

Comparison of estrogen alone or estrogen and progesterone showed no significantly increased risk with less than 5 years of replacement, and an increased risk of over 5 years of HRT.

There is a trend of an increased risk with the addition of progesterone over that of estrogen alone, but the database is still too small.

There was no difference in risk between HRT with conjugated estrogens or estradiol.

There was no increased risk with increases in dosages of HRT.

There is no difference in the increase of risk in a woman with a positive family history over that of one with a negative family history (no exaggerated risk).

The increased risk of breast cancer with HRT is actually less than that of a woman who consumes over two drinks of an alcoholic beverage per day.