Open AccessPhysical exercise reduces risk of breast cancer in Japanese women
Author(s) -
Hirose Kaoru,
Hamajima Nobuyuki,
Takezaki Toshiro,
Miura Shigeto,
Tajima Kazuo
Publication year - 2003
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/j.1349-7006.2003.tb01418.x
Subject(s) - medicine , breast cancer , body mass index , odds ratio , confidence interval , confounding , cancer , family history , population , gynecology , physical therapy , environmental health
To evaluate the effects of physical exercise on breast cancer risk, a large‐scale case‐referent study of 2376 incident breast cancer cases and 18 977 non‐cancer referents was conducted using data from the hospital‐based epidemiologic research program at Aichi Cancer Center (HERPACC). To adjust appropriately for possible confounders, we examined the effects within subgroups of the study population. The multivariable‐adjusted odds ratio (OR) was 0.81 (95% confidence interval (CI): 0.69–0.94) for twice a week or more regular exercise. We observed a decreased risk of breast cancer for women who regularly exercised for health twice a week or more, irrespective of menopausal status, and were able to detect greater risk reductions within particular subgroups, including women who were parous, without a family history or non‐drinkers. Among premenopausal women, a particularly strong protective effect of physical exercise was observed (OR=0.57, 95%CI: 0.28–1.15) for those women whose body mass index (BMI) was high (BMI≥25). In contrast, risk reduction was found (OR=0.71, 95%CI: 0.50–1.01) among postmenopausal women whose BMI was medium (BMI: 22–25). Stratification of history of stomach cancer screening to adjust modifying effects of healthy consciousness allows a more precise assessment of the protective effect of exercise twice a week or more, independent of stomach cancer screening history. This study provides evidence that physical exercise, especially exercise twice a week or more, reduces the risk of breast cancer among Japanese women. (Cancer Sci 2003; 94: 193–199)