Physical activity and breast cancer incidence in middle-aged women: A prospective cohort study

Amy J. Mertens, Carol Sweeney, Eyal Shahar, Wayne D. Rosamond, Aaron R. Folsom

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Many reports suggest that physically active women have a somewhat lower breast cancer incidence than physically inactive women. We hypothesized that indices of physical activity are associated inversely with breast cancer incidence after adjustment for confounders. The sample comprised 7994 women, aged 45-64, who participated in the Atherosclerosis Risk in Communities (ARIC) Study. Baseline physical activity was assessed by the Baecke questionnaire. Over an average follow-up of 13.1 yrs, 342 incident breast cancer cases were ascertained. After adjustment for age, race, study center, age at first live birth, age at menopause, and family history of breast cancer in a first-degree relative, there was no statistically significant association of breast cancer incidence with baseline physical activity levels for leisure, sport or work indices. Compared with the lowest quartile of physical activity, women in the highest quartile had a multivariate-adjusted hazard ratio (HR) of 1.00 (95% confidence interval (CI) = 0.64-1.54) for the leisure index, 1.31 (95% CI = 0.87-1.96) for the sport index and 0.87 (95% CI = 0.61-1.24) for the work index. Our findings do not corroborate the majority of previous reports, which implicated physical inactivity as a risk factor for breast cancer.

Original languageEnglish (US)
Pages (from-to)209-214
Number of pages6
JournalBreast Cancer Research and Treatment
Issue number2
StatePublished - May 2006


  • Breast cancer
  • Exertion
  • Physical activity
  • Prospective study
  • Women

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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