Breast Cancer

Study data from Brigham and Women's Hospital update understanding of breast cancer

Breast Cancer Library Library Home This article was published in Clinical Oncology Week, which you can subscribe to online.

"We examined whether these predictors are independently associated with breast cancer risk in a prospective study. Methods We conducted a nested case-control study within the Nurses' Health Study cohort of 253 case subjects with breast cancer and 520 control subjects. All participants were postmenopausal women who were not using postmenopausal hormones at the time of both blood collection and mammography. Plasma levels of estradiol, free estradiol, testosterone, and free testosterone were evaluated. Mammographic density was assessed by use of computer-assisted analysis of mammograms. Logistic regression models that were adjusted for matching variables and potential confounders were used to calculate relative risks (RRs) and 95% confidence intervals (Cls). All statistical tests were two-sided. Results Levels of circulating sex steroids and mammographic density were both statistically significantly and independently associated with breast cancer risk. The relative risk of breast cancer associated with mammographic density (RR for highest quartile compared with lowest quartile = 3.8, 95% Cl = 2.2 to 6.6; P-trend <.001) changed little when the analysis was adjusted for circulating estradiol (1111 = 3.9, 95% Cl = 2.2 to 6.9; P-trend <.001) or circulating testosterone (RR = 4.1, 95% Cl = 2.3 to 7.2; P-trend <-001). Circulating levels of estradiol (RR = 2.4, 95% Cl = 1.4 to 4.0) and of testosterone (RR = 2.0, 95% Cl = 1.2 to 3.1) were both associated with breast cancer risk, before and after adjustment for mammographic density. In a joint analysis of mammographic density and plasma testosterone, the risk of breast cancer was highest in the highest tertiles of both relative to the lowest tertiles of both (RR = 6.0, 95% Cl = 2.6 to 14.0). A similar pattern was observed in the joint analysis of estradiol and mammographic density (RR = 4.1, 95% Cl = 1.7 to 9.8)," wrote R.M. Tamimi and colleagues, Brigham and Women's Hospital.

The researchers concluded: "Conclusions Circulating sex steroid levels and mammographic density appear strongly and independently associated with the risk of breast cancer in postmenopausal women."

Tamimi and colleagues published their study in the Journal of the National Cancer Institute (Endogenous hormone levels, mammographic density, and subsequent risk of breast cancer in postmenopausal women. Journal of the National Cancer Institute, 2007;99(15):1178-1187).

For additional information, contact R.M. Tamimi, Brigham & Women's Hospital, Channing Laboratory, Dept. of Medical, 181 Longwood Avenue, Boston, MA 02115, USA.

Publisher contact information for the Journal of the National Cancer Institute is: Oxford University Press Inc., Journals Dept., 2001 Evans Rd., Cary, NC 27513, USA.

Keywords: United States, Boston, Breast Cancer, Breast Carcinoma, Oncology, Women's Health, Brigham and Women's Hospital.

This article was prepared by Clinical Oncology Week editors from staff and other reports. Copyright 2007, Clinical Oncology Week via NewsRx.com.