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

Jennifer A. Crozier, Alvaro Moreno-Aspitia, Karla V. Ballman, Amylou C. Dueck, Barbara A. Pockaj, Edith A. Perez

Research output: Contribution to journalArticle

22 Scopus citations

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/m2), overweight (BMI ≥25 kg/m2 and <30 kg/m2), and obese (BMI ≥30 kg/m2). 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.

Original languageEnglish (US)
Pages (from-to)2447-2454
Number of pages8
JournalCancer
Volume119
Issue number13
DOIs
StatePublished - Jul 1 2013

Keywords

  • adjuvant therapy
  • body mass index
  • obesity
  • trastuzumab

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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