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Keywords:

  • breast cancer;
  • survival;
  • mortality;
  • physical activity;
  • exercise

Abstract

BACKGROUND

Most epidemiologic studies report a reduced risk of developing breast cancer associated with higher levels of recreational physical activity, but little is known regarding its effect on prognosis.

METHODS

In this study, the authors investigated whether activity undertaken prior to diagnosis influenced breast cancer survival in a population-based cohort. A follow-up study was conducted among 1264 women ages 20 to 54 years who were diagnosed with invasive breast cancer between 1990 and 1992. Women in the study were interviewed within several months of diagnosis and were asked about their average frequency of moderate and vigorous activity at age 13 years, age 20 years, and during the year before diagnosis. With 8 to 10 years of follow-up, all-cause mortality status was determined by using the National Death Index (n = 290 deaths).

RESULTS

A modest reduction in the hazards ratio (HR) was observed for the highest quartile of activity in the year before diagnosis compared with the lowest quartile (stage-adjusted and income-adjusted HR, 0.78; 95% confidence interval [95% CI], 0.56–1.08). High activity was associated with a reduced HR among women who were overweight or obese at the time of diagnosis (HR, 0.70; 95% CI, 0.49–0.99) but not among ideal weight or underweight women (HR, 1.08; 95% CI, 0.77–1.52). A reduced HR was not evident for activity at age 13 years or 20 years or for average activity across the 3 periods studied.

CONCLUSIONS

The results of this study provided some suggestive evidence for a beneficial effect on survival of recreational physical activity undertaken in the year before diagnosis, particularly among women who are overweight or obese near the time of diagnosis. Cancer 2006. Published 2006 by the American Cancer Society.