Lifetime exercise activity and breast cancer risk among post-menopausal women

• Published in: British Journal of Cancer Vol. 80; no. 11; pp. 1852 - 1858
• Main Authors: CARPENTER, C. L, ROSS, R. K, PAGANINI-HILL, A, BERNSTEIN, L
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing Group 01.08.1999
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; Breast Neoplasms - epidemiology; Breast Neoplasms - genetics; Case-Control Studies; Energy Metabolism; Exercise; Female; Gynecology. Andrology. Obstetrics; Humans; Los Angeles - epidemiology; Mammary gland diseases; Medical sciences; Menarche; Middle Aged; Postmenopause; Pregnancy; Reference Values; Regular; Risk Factors; Socioeconomic Factors; Tumors; United States; North America; America; Los Angeles; Physical exercise; Human; Mammary gland diseases; Risk factor; Female; Case control study; Mammary gland; Malignant tumor; Epidemiology; Weight gain; Public health
• ISSN: 0007-0920; 1476-5381; 1532-1827
• DOI: 10.1038/sj.bjc.6690610

Lifetime exercise activity has been linked to breast cancer risk among young women. However, no study has specifically evaluated whether lifetime exercise activity is related to the breast cancer risk of post-menopausal women. We conducted a population-based case-control study of post-menopausal white women (1123 newly diagnosed cases and 904 healthy controls) aged 55-64 who lived in Los Angeles County, California, USA to evaluate this relationship. Although neither exercise activity from menarche to age 40 years, nor exercise after age 40 separately predicted breast cancer risk, risk was lower among women who had exercised each week for at least 17.6 MET-hours (metabolic equivalent of energy expenditure multiplied by hours of activity) since menarche than among inactive women (odds ratio (OR) = 0.55; 95% confidence interval (CI) 0.37-0.83). Exercise activity was not protective for women who gained considerable (> 17%) weight during adulthood. However, among women with more stable weight, breast cancer risk was substantially reduced for those who consistently exercised at high levels throughout their lifetime (OR = 0.42; 95% CI 0.24-0.75), those who exercised more than 4 h per week for at least 12 years (OR = 0.59; 95% CI 0.40-0.88), and those who exercised vigorously (24.5 MET-hours per week) during the most recent 10 years (OR = 0.52; 95% CI 0.32-0.85). Strenuous exercise appears to reduce breast cancer risk among post-menopausal women who do not gain sizable amounts of weight during adulthood.