Breast cancer risk and lifetime leisure-time and occupational physical activity (Sweden)

Cancer Causes Control. 2000 Jul;11(6):523-31. doi: 10.1023/a:1008900512471.


Objective: To clarify whether type and timing of physical activity affect postmenopausal breast cancer risk.

Methods: In a population-based case-control study within the Swedish female population 50-74 years of age, 3347 women with invasive, postmenopausal breast cancer (84% of all eligible) and 3455 controls (82% of all selected) reported on past leisure-time physical activity. Record linkage to decennial census data (1960-1990) provided estimates of their occupational physical activity. Odds ratios with 95% confidence intervals were estimated by multivariate logistic regression.

Results: After adjustment for potential confounders, women in sedentary occupations during their reproductive years (25-44 years of age) had a 50% higher risk for postmenopausal breast cancer, compared to those with the physically most demanding jobs. Only the most recent leisure-time physical activity was associated with a significant risk reduction. Women with the combination of sedentary jobs and lack of leisure-time exercise had a three-fold higher risk of breast cancer, compared to the physically most active both inside and outside the workplace.

Conclusion: Effects of occupational and leisure-time physical activity on breast cancer risk appear to have different latency times, and/or to be effect-modified by age or reproductive status. Although chance might explain our findings, it is advisable to consider type and timing of physical activity in future studies.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / prevention & control*
  • Case-Control Studies
  • Exercise*
  • Female
  • Humans
  • Leisure Activities
  • Logistic Models
  • Middle Aged
  • Occupations
  • Odds Ratio
  • Postmenopause
  • Reproductive History
  • Risk Factors
  • Social Class
  • Socioeconomic Factors
  • Surveys and Questionnaires
  • Sweden / epidemiology