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Final multivariate analysis of obesity and survival in patients with node-positive primary breast cancer: The ADEBAR trial.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: The prevalence of obesity increases throughout most industrialized countries. Epidemiological studies have shown not only an increase in breast cancer (BC) among obese women but also an adverse impact of obesity on BC survivors. This analysis focuses on the impact of obesity on high risk BC patients (pts) treated within the ADEBAR study protocol. Methods: The ADEBAR Trial compared 4 cycles of EC followed by 4 cycles of Doc vs. 8 cycles of FEC (120) in pts with primary BC (>=4LN). 1500 pts have been accrued from sep/01 through may/05. For this analysis data of 1361 pts has been analyzed about the impact of obesity on disease free survival. Therefore pts have been grouped to either underweight (BMI<18.5kg/m²), normal weight (BMI18.5-25kg/m²), overweight (25kg/m<BMI<=30kg/m²) or obese (BMI>30). Results: 13 pts (1.0%) were underweight, 557 pts (40.9%) were normal weight, 491 pts (36.1%) were overweight, 300 pts (22.0%) were obese at the time of study enrollment. After a follow up period of 60 months 87.5% of the underweight group, 70.4% of the normal weight group, 70.7% of the overweight group and 58.6% of the obese group were alive with no signs of recurrent disease (Chi-square=9.355; p< 0.0249). In univariate analysis also overall survival was significantly worse in the obese pts group (p = 0.014). There was no significant difference in survival between patients with normal weight and moderate overweight, respectively. In multivariate analysis, accounting for tumor size, lymph node status, histopathological grading, hormone receptor status, age, menopausal status and type of chemotherapy, not a BMI of greater than 25, but a BMI of greater than 30 was predictive for a significant higher risk for death. (hazard ratio 1.67 [1.14-2.45], p= .008. Additionally, a significant incremental effect for every BMI point could be shown, with an increased hazard ratio of 0.7 % for every kg per square meter. Conclusions: In conclusion, the results of this analysis confirm previous data on the detrimental impact of obesity on the survival of BC patients in this homogeneous group of individuals with high risk disease undergoing chemotherapy.