Physical activity and risk of recurrence and mortality in breast cancer survivors: findings from the LACE study.
BACKGROUND
Identifying modifiable factors that reduce the risk of recurrence and improve survival in breast cancer survivors is a pressing concern. The purpose of this study was to examine the association of physical activity following diagnosis and treatment with the risk of breast cancer recurrence and mortality and all-cause mortality in women with early-stage breast cancer.


METHODS
The sample consisted of 1,970 women from the Life After Cancer Epidemiology study, a prospective investigation of behavioral risk factors and health outcomes. Self-reported frequency and duration of work-related, household and caregiving, recreational, and transportation-related activities during the six months prior to enrollment were assessed. Outcomes were ascertained from electronic or paper medical charts. Hazard ratios and 95% confidence intervals were estimated from delayed entry Cox proportional hazards models.


RESULTS
Although age-adjusted results suggested that higher levels of physical activity were associated with reduced risk of recurrence and breast cancer mortality (P for trend = 0.05 and 0.07, respectively for highest versus lowest level of hours per week of moderate physical activity), these associations were attenuated after adjustment for prognostic factors and other confounding variables (P for trend = 0.36 and 0.26). In contrast, a statistically significant protective association between physical activity and all-cause mortality remained in multivariable analyses (hazard ratio, 0.66; 95% confidence interval, 0.42-1.03; P for trend = 0.04).


CONCLUSIONS
These findings do not support a protective effect of physical activity on breast cancer recurrence or mortality but do suggest that regular physical activity is beneficial for breast cancer survivors in terms of total mortality.
Sternfeld
Barbara
B
Division of Research, Kaiser Permanente, 2000 Broadway, Oakland, CA 94612, USA. bxs@dor.kaiser.org
Weltzien
Erin
E
Quesenberry
Charles P
CP
Castillo
Adrienne L
AL
Kwan
Marilyn
M
Slattery
Martha L
ML
Caan
Bette J
BJ
D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000401:mortality*; D002140:California / Q000453:epidemiology; D002423:Cause of Death; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D009364:Neoplasm Recurrence, Local / Q000401:mortality*; D017063:Outcome Assessment, Health Care; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D017741:Survivors; D014589:Utah / Q000453:epidemiology