Physical Activity and Breast Cancer Risk in Postmenopausal Women: the SHAPE Study
Physical activity has been associated with a decreased risk for breast cancer. The
biological mechanism(s) underlying the association between physical activity and breast
cancer is not clear. Most prominent hypothesis is that physical activity may protect against
breast cancer through reduced lifetime exposure to endogenous hormones. Another hypothesis
is that physical activity prevents overweight and abdominal adiposity.
In this intervention study, 189 sedentary postmenopausal women who are aged 50-69 years are
randomly allocated to an intervention or a control group. The intervention consists of an
1-year moderate-to-vigorous intensity aerobic and strength training exercise programme.
Participants allocated to the control group are requested to retain their habitual exercise
pattern. Primary study parameters measured at baseline, at four months and at 12 months are:
serum concentrations of endogenous estrogens, endogenous androgens, sex hormone binding
globulin and insulin. Other study parameters include: amount of total and abdominal fat,
weight, BMI, body fat distribution, physical fitness, blood pressure and lifestyle factors.
This study will contribute to the body of evidence relating physical activity and breast
cancer risk and will provide insight into possible mechanisms through which physical
activity might be associated with reduced risk of breast cancer in postmenopausal women.
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind, Primary Purpose: Prevention
Serum concentrations of endogenous estrogens: estradiol (total, free), estrone, estrone sulfate
Jantine Schuit, PhD
Dutch Institute of Public Health and the Environment
Netherlands: The Central Committee on Research Involving Human Subjects (CCMO)