Breast cancer dropped in tandem with HT in California

October 1, 2007

A drop in hormone therapy (HT) use in California was mirrored by a drop in breast cancer rates, with counties with the biggest decline in HT having a greater decline in cancer, according to the results of a large population-based study published in the Aug.

A drop in hormone therapy (HT) use in California was mirrored by a drop in breast cancer rates, with counties with the biggest decline in HT having a greater decline in cancer, according to the results of a large population-based study published in the Aug. 10 issue of the Journal of Clinical Oncology. At the same time, mammography rates remained stable, suggesting that the cancer decline may indeed have been due to a drop in HT use.

Anthony Robbins, MD, PhD, of the California Cancer Registry in Sacramento, Calif., and a colleague analyzed data from the registry that included nearly 3 million non-Hispanic white women aged 45 to 74. The researchers divided counties into three groups based on estrogen-progestin hormone therapy (EPHT) use in 2001. They then analyzed trends in the age-adjusted incidence of breast cancer in these counties compared with changes in hormone use.

Large regional differences were detected in the incidence of breast cancer and EPHT use between 2001 and 2004. Breast cancer incidence declined by 8.8% in counties with the smallest change in EPHT, by 13.9% in counties with an intermediate reduction, and by 22.6% in counties with the largest drop in EPHT.

Robbins AS, Clarke CA. Regional changes in hormone therapy use and breast cancer incidence in California from 2001 to 2004. J Clin Oncol. 2007;25:3437-3439.