Decline in physical functioning in first 2 years after breast cancer diagnosis to predict survival in older women.

Abstract

e11003 Background: Breast cancer patients often experience a decline in physical functioning following cancer diagnosis. Although most patients recover after treatment, some patients do not. These changes may be magnified in older women with comorbid conditions and could impact survival outcomes. Methods: We used longitudinal data from a prospective cohort study of women 65+ years of age, recruited shortly after diagnosis of early stage breast cancer, to examine changes in self-reported physical functioning measured with the Physical Function Index (PF-10) of the Medical Outcomes Study Short Form-36 (SF-36). Outcomes were constructed for small (0.2 SD), medium (0.5 SD), and large (0.8 SD) decline in the PF-10 measurement over two intervals 1) 3 to 15 months following cancer diagnosis, encompassing treatment and early recovery, and 2) 3 to 27 months following cancer diagnosis, in order to detect sustained recovery versus persistent decline. Cox-proportional hazards regression was used to examine association between survival and decline in PF-10 scores. Results: A large (> 0.8 SD) decline in PF-10 scores from 3 to 27 months predicted shorter 10 year survival (HR=1.37, 95% CI 1.07-1.74). Persistent decline at 27 months was associated with less education, higher baseline PF-10, increased comorbidity, and lack of exercise at baseline. Conclusions: Older women with breast cancer who experience a large and persistent decline in PF-10 are at increased mortality risk. Future research should examine the value of clinical assessment of physical function as a marker for mortality and test interventions to prevent decline in physical function to improve post-treatment survival outcomes.