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Cancer. 2013 Jul 1;119(13):2447-54. doi: 10.1002/cncr.28051. Epub 2013 Apr 12.

Effect of body mass index on tumor characteristics and disease-free survival in patients from the HER2-positive adjuvant trastuzumab trial N9831.

Author information

1
Department of Internal Medicine, Mayo Clinic, Jacksonville, Florida 32224, USA.

Abstract

BACKGROUND:

Data suggest that weight, and specifically body mass index (BMI), plays a role in breast cancer development and outcome. The authors hypothesized that there would be a correlation between BMI and clinical outcome in patients with early stage, human epidermal receptor 2 (HER2)-positive breast cancer enrolled in the N9831 adjuvant trial.

METHODS:

Patients were grouped according to baseline BMI as follows: normal (BMI <25 kg/m(2)), overweight (BMI ≥25 kg/m(2) and <30 kg/m(2)), and obese (BMI ≥30 kg/m(2)). Disease-free survival (DFS) was estimated using the Kaplan-Meier method. Comparisons between treatment arms A, B, and C (chemotherapy with or without trastuzumab) were performed using a stratified Cox proportional hazards model.

RESULTS:

Analysis was completed on 3017 eligible patients. Obese patients were more likely to be older and postmenopausal (P < .0001 for both), to have larger tumors (P = .002), and to have positive lymph nodes (P = .004). In the pooled analysis cohort, differences in DFS among the BMI groups were statistically significant (5-year DFS rate: 82.5%, 78.6%, and 78.5% for normal weight, overweight, and obese women, respectively; log-rank P = .02). The adjusted hazard ratio comparing the DFS of overweight women with the DFS of normal women was 1.30 (95% confidence interval, 1.06-1.61); and, comparing the DFS of obese women with the DFS normal women, the adjusted hazard ratio was 1.31 (95% confidence interval, 1.07-1.59). There were no statistically significant differences in DFS by weight group for women within any trial arm.

CONCLUSIONS:

Patients with early stage, HER2-positive breast cancer and normal BMI had a better 5-year DFS compared with overweight and obese women. The current results indicated that adjuvant trastuzumab improves clinical outcome regardless of BMI.

PMID:
23585192
PMCID:
PMC3686994
DOI:
10.1002/cncr.28051
[Indexed for MEDLINE]
Free PMC Article

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