Physical activity before and after breast cancer diagnosis and survival - the Norwegian women and cancer cohort study

BMC Cancer. 2015 Dec 16;15:967. doi: 10.1186/s12885-015-1971-9.

Abstract

Background: The main aim of this study was to investigate pre- and post-diagnostic physical activity (PA) levels, as well as changes in pre- and post-diagnostic PA levels, and their association with all-cause and breast cancer-specific mortality in women with breast cancer. Our study will add to the knowledge on whether a modifiable behavior such as PA can improve survival.

Methods: We included 1,327 women with breast cancer from the population-based Norwegian Women and Cancer study, which enrolled women from 1991 to 2003. Breast cancer cases were identified through linkage to the Cancer Registry of Norway; date and cause of death were obtained from the National Register for Causes of Death through 31 December 2012. Self-reported pre- and post-diagnostic PA levels were assessed, and Cox proportional hazard regression and spline regression were used to evaluate the associations.

Results: Pre-diagnostic PA levels were not associated with all-cause or breast cancer-specific mortality. Post-diagnostic PA levels were associated with a significant trend (P<0.001) of decreased all-cause and breast cancer-specific mortality, which was stronger among older women (aged 50-74 years) and did not differ across categories of body mass index. All-cause mortality (hazard ratio [HR]=1.76, 95% confidence interval [CI] 1.21-2.56) and breast cancer-specific mortality (HR=2.05, 95% CI 1.35-3.10) increased among women who reduced their post-diagnostic PA level. These values were similar among women whose maintained an inactive PA level pre- and post-diagnosis.

Conclusion: Overall, we observed a dose-response trend, with an inverse association between increased post-diagnostic PA level and all-cause and breast cancer-specific mortality, as well as a higher mortality risk among women who reduced their post-diagnostic PA levels. Our results are very promising for women with breast cancer, and indicate that health care professionals should consider adding PA as a part of primary cancer treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Breast Neoplasms / mortality*
  • Cohort Studies
  • Exercise / physiology*
  • Female
  • Humans
  • Middle Aged
  • Motor Activity / physiology
  • Norway / epidemiology
  • Surveys and Questionnaires