Poor physical health predicts time to additional breast cancer events and mortality in breast cancer survivors

Background: Health-related quality of life has been hypothesized to predict time to additional breast cancer events and all-cause mortality in breast cancer survivors. Methods: Women with early-stage breast cancer (n=2967) completed the SF-36 (mental and physical health-related quality of life) and standardized psychosocial questionnaires to assess social support, optimism, hostility, and depression prior to randomization into a dietary trial. Cox regression was performed to assess whether these measures of quality of life and psychosocial functioning predicted time to additional breast cancer events and all-cause mortality; hazard ratios were the measure of association. Results: There were 492 additional breast cancer events and 301 deaths occurred over a median 7.3 years (range: 0.01-10.8 years) of follow-up. In multivariate models, poorer physical health was associated with both decreased time to additional breast cancer events and all-cause mortality (p trend=0.005 and 0.004, respectively), while greater hostility predicted additional breast cancer events only (p trend=0.03). None of the other psychosocial variables predicted either outcome. The hazard ratios comparing persons with poor (bottom two quintiles) to better (top three quintiles) physical health were 1.42 (95% CI: 1.16, 1.75) for decreased time to additional breast cancer events and 1.37 (95% CI: 1.08, 1.74) for all-cause mortality. Potentially modifiable factors associated with poor physical health included higher body mass index, lower physical activity, lower alcohol consumption, and more insomnia (p<0.05 for all). Conclusion: Interventions to improve physical health should be tested as a means to increase time to additional breast cancer events and mortality among breast cancer survivors.