Endogenous Hormone Levels, Mammographic Density, and Subsequent Risk of Breast Cancer in Postmenopausal Women
- From: MarilynMann <mannm@xxxxxxxxxxx>
- Date: Thu, 23 Aug 2007 06:23:08 -0700
JNCI Journal of the National Cancer Institute 2007 99(15):1178-
Endogenous Hormone Levels, Mammographic Density, and Subsequent Risk
of Breast Cancer in Postmenopausal Women
Rulla M. Tamimi, Celia Byrne, Graham A. Colditz, Susan E. Hankinson
Affiliations of authors: Channing Laboratory, Department of Medicine,
Brigham and Women's Hospital and Harvard Medical School, Boston, MA
(RMT, SEH); Department of Epidemiology, Harvard School of Public
Health, Boston, MA (RMT, GAC, SEH); Cancer Genetics and Epidemiology
Program, Lombardi Comprehensive Cancer Center, Georgetown University,
Washington, DC (CB); Department of Surgery, Washington University
School of Medicine, St. Louis, MO (GAC)
Correspondence to: Rulla M. Tamimi, ScD, Channing Laboratory,
Department of Medicine, Brigham and Women's Hospital and Harvard
Medical School, 181 Longwood Ave, Boston, MA 02115 (e-mail:
rulla.tamimi@xxxxxxxxxxxxxxxxxxxx).
Background: Mammographic density and circulating sex hormones are two
well-confirmed predictors of breast cancer risk. Whether mammographic
density reflects levels of endogenous sex hormones is unclear. 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 (CIs). 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% CI = 2.2 to 6.6; Ptrend<.001) changed
little when the analysis was adjusted for circulating estradiol (RR =
3.9, 95% CI = 2.2 to 6.9; Ptrend<.001) or circulating testosterone (RR
= 4.1, 95% CI = 2.3 to 7.2; Ptrend<.001). Circulating levels of
estradiol (RR = 2.4, 95% CI = 1.4 to 4.0) and of testosterone (RR =
2.0, 95% CI = 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% CI = 2.6 to 14.0). A
similar pattern was observed in the joint analysis of estradiol and
mammographic density (RR = 4.1, 95% CI = 1.7 to 9.8).
Conclusions: Circulating sex steroid levels and mammographic density
appear strongly and independently associated with the risk of breast
cancer in postmenopausal women.
--------------------------------------------------------------------------------
CONTEXT AND CAVEATS
Prior knowledge
Mammographic density and circulating sex hormones are two confirmed
predictors of breast cancer risk, but it is unclear whether the risk
associated with mammographic density is primarily related to levels of
endogenous sex hormones.
Study design
A nested case-control study within the Nurses' Health Study cohort
with 253 case subjects with breast cancer and 520 control subjects who
were postmenopausal at the time of blood collection and mammographic
examination.
Contribution
Among postmenopausal women, levels of circulating sex steroids and
mammographic density were both statistically significantly and
independently associated with breast cancer risk.
Implications
The mechanism by which mammographic density increases the risk of
breast cancer among postmenopausal women is independent of the levels
of circulating sex steroid hormones.
Limitations
Circulating levels of steroid hormones were used as a proxy for the
more biologically relevant measure of the levels of steroid hormones
in breast tissues.
* * *
This study has nothing to do with CVD, but I'm posting it anyway.
Marilyn
.
- Prev by Date: Jay Heinecke/HDL composition
- Next by Date: Re: Imminent Bird Flu Pandemic in Humans
- Previous by thread: Jay Heinecke/HDL composition
- Next by thread: Statins ?
- Index(es):
Relevant Pages
|
