TY - JOUR
T1 - Sex hormone levels and risks of estrogen receptor-negative and estrogen receptor-positive breast cancers
AU - Farhat, Ghada N.
AU - Cummings, Steven R.
AU - Chlebowski, Rowan T.
AU - Parimi, Neeta
AU - Cauley, Jane A.
AU - Rohan, Thomas E.
AU - Huang, Alison J.
AU - Vitolins, Mara
AU - Hubbell, F. Allan
AU - Manson, Joann E.
AU - Cochrane, Barbara B.
AU - Lane, Dorothy S.
AU - Lee, Jennifer S.
PY - 2011/4/6
Y1 - 2011/4/6
N2 - BackgroundEndogenous sex hormone levels are associated with risks of breast cancer overall and estrogen receptor (ER)-positive breast tumors; however, their associations with ER-negative tumors remain unclear.MethodsIn a case-cohort study within the Women's Health Initiative Observational Study among postmenopausal women aged 50-79 years, we examined associations between endogenous testosterone and estradiol levels and the risks of ER-negative and ER-positive breast cancers. Serum levels of bioavailable testosterone and estradiol were assessed at the baseline visit in 317 invasive breast cancer case subjects and in a subcohort of 594 women. Bioavailable sex hormone levels were calculated using the total hormone level and the sex hormone-binding globulin concentration (measured by radioimmunoassays and a chemiluminescent immunoassay, respectively). Cox proportional hazards regression was used for statistical analysis. All statistical tests were two-sided.ResultThe unadjusted absolute rates of ER-negative breast cancer for testosterone quartiles 1-4 were 0.34, 0.20, 0.23, and 0.21 per 10000 person-years, respectively. Compared with women in the lowest quartile of testosterone level, those in quartile 2 had a 56% lower risk of ER-negative cancer (hazard ratio [HR] = 0.44, 95% confidence interval [CI] = 0.23 to 0.85), those in quartile 3 had a 45% lower risk (HR = 0.55, 95% CI = 0.30 to 1.01), and those in quartile 4 had a 49% lower risk (HR = 0.51, 95% CI = 0.28 to 0.94), independent of other risk factors. Estradiol level was not associated with ER-negative breast cancer. ER-positive breast cancer risk increased with higher testosterone levels (Ptrend =. 04), but this trend was not statistically significant after adjustment for estradiol (Ptrend =. 15). ER-positive cancer risk was approximately twofold higher in women with estradiol levels in quartiles 2-4 compared with women in quartile 1, independent of risk factors.ConclusionHigher serum levels of bioavailable testosterone are associated with lower risks of ER-negative breast cancer in postmenopausal women.
AB - BackgroundEndogenous sex hormone levels are associated with risks of breast cancer overall and estrogen receptor (ER)-positive breast tumors; however, their associations with ER-negative tumors remain unclear.MethodsIn a case-cohort study within the Women's Health Initiative Observational Study among postmenopausal women aged 50-79 years, we examined associations between endogenous testosterone and estradiol levels and the risks of ER-negative and ER-positive breast cancers. Serum levels of bioavailable testosterone and estradiol were assessed at the baseline visit in 317 invasive breast cancer case subjects and in a subcohort of 594 women. Bioavailable sex hormone levels were calculated using the total hormone level and the sex hormone-binding globulin concentration (measured by radioimmunoassays and a chemiluminescent immunoassay, respectively). Cox proportional hazards regression was used for statistical analysis. All statistical tests were two-sided.ResultThe unadjusted absolute rates of ER-negative breast cancer for testosterone quartiles 1-4 were 0.34, 0.20, 0.23, and 0.21 per 10000 person-years, respectively. Compared with women in the lowest quartile of testosterone level, those in quartile 2 had a 56% lower risk of ER-negative cancer (hazard ratio [HR] = 0.44, 95% confidence interval [CI] = 0.23 to 0.85), those in quartile 3 had a 45% lower risk (HR = 0.55, 95% CI = 0.30 to 1.01), and those in quartile 4 had a 49% lower risk (HR = 0.51, 95% CI = 0.28 to 0.94), independent of other risk factors. Estradiol level was not associated with ER-negative breast cancer. ER-positive breast cancer risk increased with higher testosterone levels (Ptrend =. 04), but this trend was not statistically significant after adjustment for estradiol (Ptrend =. 15). ER-positive cancer risk was approximately twofold higher in women with estradiol levels in quartiles 2-4 compared with women in quartile 1, independent of risk factors.ConclusionHigher serum levels of bioavailable testosterone are associated with lower risks of ER-negative breast cancer in postmenopausal women.
UR - http://www.scopus.com/inward/record.url?scp=79953893331&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79953893331&partnerID=8YFLogxK
U2 - 10.1093/jnci/djr031
DO - 10.1093/jnci/djr031
M3 - Article
C2 - 21330633
AN - SCOPUS:79953893331
SN - 0027-8874
VL - 103
SP - 562
EP - 570
JO - Journal of the National Cancer Institute
JF - Journal of the National Cancer Institute
IS - 7
ER -
