women in steady exercise research [formerly women, oxidative stress, exercise and estrogens (wosee)]

Conditions: Breast Cancer; Obesity

Summary: rationale: exercising regularly may lower the risk of breast cancer. purpose: this randomized clinical trial is studying how well exercise prevents breast cancer in healthy young women.

objectives: primary * compare the changes in urine levels of a stable marker of oxidative stress (f_2-isoprostanes) in healthy young women who undergo exercise training during 4 menstrual cycles vs no exercise. secondary * assess the changes in other metabolic factors that explain the association between physical activity and breast cancer, including: estrogen metabolism (estrone, estradiol, estriol, 2-ohe_1, 2-ohe_2, 2-meohe_1, 2-meohe_2, 4-ohe_1, 4-ohe_2 \[as well as ratios of these metabolites\], insulin-like growth factor (igf)-1 (as well as igf-binding proteins-1, -2, and -3, insulin, glucose, body composition (including body mass index, lean mass, and body fat \[dexa scan\]). outline: this is a randomized, controlled study. participants are stratified according to baseline body fat percentage and age (18 to 24 years vs 25 to 30 years). participants are randomized to 1 of 2 intervention arms. * arm i: participants exercise for 30 minutes 5 times a week. the intensity of exercise is increased every 4 weeks. the exercise regimen continues for up to 4 menstrual cycles. * arm ii: participants are observed for 4 menstrual cycles. participants in both arms undergo 24-hour collection of urine on days 7, 8, and 9 of menstrual cycles 1 and 6. f_2-isoprostanes are measured via gas chromatography-mass spectrometry (gc/ms). estrogens are also measured by gc/ms and include e_1, e_2, e_3, 2-ohe_1, 2-ohe_2, 4-ohe_1, 4-ohe_2, 2-mee_1, 2-mee_2, 4-mee_1, 4-mee_2, and 16ohe_1. participants undergo blood collection, body mass measurement by dual-energy x-ray absorptiometry, and a fitness assessment twice during the 6-month study. projected accrual: a total of 400 participants will be accrued.

Eligibility criteria:
inclusion criteria: * healthy women * self-reported menstrual cycle length of 25-35 days within the past 2 months * nonsmoker * sedentary (exercise \< 3 times weekly within the past 6 months) * intact ovaries and uterus * no history of gynecological problems (e.g., fibroids, endometriosis, polycystic ovary syndrome) * female * premenopausal * body mass index 18.5 to 40 * stable weight (no changes ≥ 10% within the past year) exclusion criteria: * no pregnancy or breast feeding within the past 6 months * no plans to become pregnant during study treatment * no cancer within the past 5 years except for nonmelanoma skin cancers * no medical condition that would prohibit participation in a vigorous program of weight-bearing aerobic exercise including, but not limited to, any of the following: * fibromyalgia * chronic fatigue syndrome * metabolic disorders * recent cardiovascular event * orthopedic limitations * psychiatric disorders requiring antipsychotic drugs * no uncontrolled hypertension (systolic blood pressure \[bp\] \> 160 mm hg and/or diastolic bp \> 99 mm hg) * no more than 7 alcoholic beverages per week * no injected hormonal contraceptive use within the past year * more than 6 months since prior use of intrauterine device * more than 3 months since prior oral or patch hormone contraceptives * no medication that would prohibit participation in a vigorous program of weight-bearing aerobic exercise

Keywords: exercise breast cancer prevention obesity estrogen metabolism oxidative stress igf-1