title: Physical exercise reduces risk of breast cancer in Japanese women.
abstract: 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 (BM > or = 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.
authors.affiliation: Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681. khirose@aichi-cc.jp
authors.forename: Kaoru
authors.initials: K
authors.lastname: Hirose
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamajima
authors.forename: Toshiro
authors.initials: T
authors.lastname: Takezaki
authors.forename: Shigeto
authors.initials: S
authors.lastname: Miura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tajima
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000428:Alcohol Drinking / Q000453:epidemiology; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D015444:Exercise; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008403:Mass Screening / Q000706:statistics & numerical data; D008875:Middle Aged; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data; D017698:Postmenopause; D017697:Premenopause; D011446:Prospective Studies; D017584:Reproductive History; D012306:Risk; D012907:Smoking / Q000453:epidemiology; D013274:Stomach Neoplasms / Q000453:epidemiology; D011795:Surveys and Questionnaires