The finding was reported by the Endogenous Hormones and Breast Cancer Collaborative Group. Joanne F. Dorgan, M.P.H, Ph.D., a member of the Population Science Division at Fox Chase Cancer Center is a lead investigator of one of nine cohorts included in the analysis.

"The overall results show that postmenopausal women with higher serum sex hormone levels including estradiol and testosterone were twice as likely to develop breast cancer," explained Dorgan.

"Associations between serum sex hormone levels and risk of developing breast cancer were not different in women who donated blood closer in time to diagnosis, indicating higher hormone levels in these women were not a preclinical finding."

In each of the nine cohorts included in the analysis, women who donated blood were followed for an average of 2 to 12 years. During that time 663 women developed breast cancer. Hormones in their blood were compared with the hormones of 1,765 women who were the same age when blood was donated as the women who developed breast cancer.

“The results are highly statistically significant and were not altered when we adjusted for established risk factors for breast cancer,” added Dorgan. Some of the known risk factors for breast cancer are never having been pregnant, early menarche, and in postmenopausal women, late menopause, use of hormone replacement therapy, and being overweight."

“More analyses are planned to increase our understanding of what factors influence a woman's risk of breast cancer," Dorgan stated. "The ultimate goal is to identify ways to prevent breast cancer, which affects 193,700 women in the United States annually. ” The Endogenous Hormones and Breast Cancer Collaborative Group is international consortium that includes epidemiologists from the United States, England, Italy, and Japan. The group conducts research on the relationship of endogenous hormones to breast cancer development. Each of the nine cohorts in which the association of sex hormones with breast cancer has been prospectively evaluated is represented in this study. For the current analysis, researchers from each of the nine cohorts pooled their data so they could obtain more precise estimates of the risk of developing breast cancer associated with elevated estrogen and androgen levels. The larger sample size achieved by pooling the data also allows for analyses of subsets of interest.

The nine cohorts and the principal investigators who make up the Endogenous Hormones and Breast Cancer Collaborative Group include: the Columbia, MO. cohort (JF Dorgan), the Guernsey, UK cohort (TJ Key); Nurses' Health Study cohort (SE Hankinson), New York University Women's Health Study cohort (PG Toniolo), the ORDET, Italy cohort (F Berrino), the Rancho Bernardo cohort (E Barrett-Connor), the RERF, Japan cohort (M Kabuto), the SOF cohort (JA Cauley), and the Washington County, MD cohort (KJ Helzlsouer). Fox Chase Cancer Center, one of the nation’s first comprehensive cancer centers designated by the National Cancer Institute in 1974, conducts basic and clinical research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center’s web site at http://www.fccc.edu or call 1-888-FOX CHASE.

Note: If no author is given, the source is cited instead.

• Breast Cancer
• Women's Health
• Cancer
• Menopause
• Colon Cancer
• Ovarian Cancer

• Hormone replacement therapy
• Menopause
• Hysterectomy
• Estrogen
• Breast reconstruction
• Breast cancer