Decline in Hormone Use Linked to Drop in Breast Cancer Incidence

A new study finds that a recent drop in postmenopausal hormone use was soon followed by a decline in breast cancer incidence. Data from Kaiser Permanente’s (a large health-delivery system) northern California region showed that between 2001 and 2003 there was a 68 percent decline in the use of estrogen- or progestin-containing therapies and a 36 percent decline in estrogen-only therapy use among Kaiser Permanente members. For the same time period, breast cancer incidence in this group dropped 10 percent. The authors caution that these figures, while suggestive, do not establish cause and effect.