Long-Term Estrogen Use Tied to Breast Cancer Risk

Postmenopausal women who take estrogen therapy for long periods of time may have a significantly increased risk of breast cancer, a new study suggested.

These findings further demonstrate the potential role of postmenopausal estrogen therapy in elevated breast cancer risk, which is likely due to estrogen’s promotive role in breast cancer.

“We suggest that a woman's breast cancer risks be seriously considered when she is prescribed long-term estrogen,” the authors of the study wrote.

The authors arrived at their conclusion following a cohort study of 454 female members of a large health maintenance organization located in northern California.

Among women who had taken estrogen for at least 5 years (n = 232), the average duration of use was 17.2 years compared with non-users (n = 222).

Ultimately, the results of the study indicated that 26 (11.2%) estrogen users had developed breast cancer compared with 9 (4.1%) non-users by the end of 1995 (relative risk [RR] 2.8).

However, the RR for estrogen decreased to 2.0 following adjustment for age and multiple breast cancer risk factors, including breast cancer surveillance.

—Christina Vogt

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