Physical activity, disability, and the risk of hospitalization for breast cancer among older women

Background. A recent investigation of physical activity, disability, and th e risk of breast cancer among older women in the Iowa 65+ Rural Health Stud y reported a decreased risk of breast cancer among women with any disabilit y compared with physically capable but inactive women (relative risk [RR] = 0.4, 95% confidence interval [CI] 0.2-0.9). Because of the intriguing natu re of that association, those investigators urged replication before drawin g any conclusions. Methods. We replicated the Iowa approach using the Longitudinal Study on Ag ing (LSOA), a nationally representative, prospective cohort study. The 3131 community-dwelling women for whom we had complete data for these analyses ranged in age from 70 to 98 years old at baseline in 1984. Using ICD9-CM 17 4 codes. linked Medicare hospital claims identified 77 women with hospitali zations for breast cancer between 1984 and 1991. Multivariable proportional hazards regression was used to model the risk for this event among disable d, inactive, moderately active, and highly active women. Results, No significant association between disability in older women and t he risk of hospitalization for breast cancer relative to inactive older wom en was detected (adjusted hazard ratio [AHR]-0.78, 95% CI 0.41-1.5). Highly active older women had a significantly reduced risk of hospitalization for breast cancer (AHR-0.42, 95% CI 0.19-0.95). Conclusion. The intriguing finding from the Iowa 65+ Rural Health Study tha t disabled older women's risk for breast cancer was reduced could not be re plicated in the LSOA, although power was limited. Highly active older woole n. however, had a significantly lower risk for breast cancer in both studie s.