Does the increase of endogenous steroid hormone levels also affect breast cancer risk in Chinese women? A case-control study in Chongqing, China

Accumulating epidemiological evidence suggests that sex steroid hormones are positively associated with the development of breast cancer. However, most of these studies were conducted among Caucasian women and few have been carried out in China. To determine whether the associations of sex steroid hormone levels with breast cancer risk observed by and large in Caucasian populations are also evident in Chinese women, we conducted a case–control study in Chongqing, China. The study included 367 incident breast cancer patients and 367 healthy controls matched on menstrual status, age and periods of blood collection in the menstrual cycle. Plasma concentrations of estradiol, progesterone, testosterone, dehydroepiandrosterone sulfate (DHEAS) and sex hormone binding globulin (SHBG) were determined by electrochemiluminescene immunoassay (ECLIA). Conditional logistic regression analysis was performed to examine their associations with breast cancer risk. From comparisons of upper and lower tertiles, we observed statistically significant positive associations with breast cancer risk for plasma estradiol levels in follicular phase (adjusted odds ratio [OR] = 5.48, 95% confidence interval [CI] = 1.58–18.97), luteal phase (OR = 4.23, CI = 1.65–10.87) and postmenopausal (OR = 2.67, CI = 1.20–5.93); for progesterone levels in luteal phase (OR = 3.11, CI = 1.28–7.56), and for testosterone levels in postmenopausal (OR = 2.83, CI = 1.26–6.35). No significant association was found with DHEAS or SHBG. Our study suggests that high circulating levels of estradiol and testosterone are positively associated with increased breast cancer risk in Chinese women, which are generally consistent with the observations in Caucasian populations. © 2008 Wiley-Liss, Inc.