Hormone Replacement Therapy Increases Risk of Lobular Breast Cancer

January 2008

Hormone replacement therapy (HRT) increases a woman’s risk of developing lobular breast cancer by 300 percent, reports a study published in the January issue of Cancer, Epidemiology, Biomarkers & Prevention. While it has long been known that HRT increases the risk of breast cancer, this study is a definitive beginning in identifying how the hormones affect the risk of developing different types of breast cancer.

The authors of the study also found that the cancer risk appears after three years of HRT treatment, earlier than the five-year period cited by previous research. Lobular breast cancer, which develops in the areas of the breast containing milk-producing glands, accounts for 10 percent of invasive breast cancer. Cases of invasive lobular cancer rose by 52 percent in the United States between 1987 and 1999.

It is estimated that 57 million prescriptions for hormone replacement therapy drugs are filled in the United States every year. Women are advised to use HRT drugs in the lowest effective dose for the shortest period of time possible with periodic reevaluation by a physician.