RT Journal Article
SR Electronic
T1 Usual Physical Activity and Endogenous Sex Hormones in Postmenopausal Women: The European Prospective Investigation into Cancer–Norfolk Population Study
JF Cancer Epidemiology Biomarkers & Prevention
JO Cancer Epidemiol Biomarkers Prev
FD American Association for Cancer Research
SP 900
OP 905
DO 10.1158/1055-9965.EPI-06-0745
VO 16
IS 5
A1 Chan, Mei-Fen
A1 Dowsett, Mitch
A1 Folkerd, Elizabeth
A1 Bingham, Sheila
A1 Wareham, Nicholas
A1 Luben, Robert
A1 Welch, Ailsa
A1 Khaw, Kay-Tee
YR 2007
UL http://cebp.aacrjournals.org/content/16/5/900.abstract
AB Background: Short-term trials indicate that intensive physical activity may influence endogenous sex hormone concentrations. However, the relationship between usual daily physical activity and endogenous hormones in postmenopausal women in the general population is still uncertain. Objective and Methods: To determine the relationship between usual physical activity and endogenous sex hormones in postmenopausal women. A cross-sectional population-based study of 2,082 postmenopausal women ages 55 to 81 years, residing in the general community of Norfolk, United Kingdom, and not currently using hormone replacement therapy were chosen to participate. Physical activity in the past 1 year was assessed using a validated questionnaire, and endogenous sex hormone and sex hormone–binding globulin (SHBG) concentrations were determined. Results: Usual physical activity levels were inversely associated with circulating concentrations of testosterone and estradiol, testosterone/SHBG ratio, and positively associated with SHBG. These associations were only slightly attenuated after adjusting for potential covariates including body mass index, smoking status, alcohol intake, and reproductive variables. Testosterone concentrations and testosterone/SHBG ratios were 19% [95% confidence interval (95% CI), 9-27%, P < 0.001] and 24.0% (95% CI, 13-34% P < 0.001) lower, respectively, whereas estradiol concentrations were 6% (95% CI, 0-12%; P < 0.05) lower in the highest compared with lowest activity levels, respectively. A decreasing trend for the estradiol/SHBG ratio and 17α-hydroxyprogesterone concentrations was also observed. Androstenedione levels did not differ significantly according to physical activity. Conclusions: Higher usual physical activity levels among postmenopausal women seem to be related to lower endogenous testosterone and estradiol concentrations. This may be one mechanism that could partly explain the reported inverse relationship between physical activity and breast cancer risk in some studies. (Cancer Epidemiol Biomarkers Prev 2007;16(5):900–905)