Breast Cancer Research and Treatment

, Volume 132, Issue 2, pp 729–739

Pre-diagnosis body mass index and survival after breast cancer in the After Breast Cancer Pooling Project

  • Marilyn L. Kwan
  • Wendy Y. Chen
  • Candyce H. Kroenke
  • Erin K. Weltzien
  • Jeannette M. Beasley
  • Sarah J. Nechuta
  • Elizabeth M. Poole
  • Wei Lu
  • Michelle D. Holmes
  • Charles P. QuesenberryJr.
  • John P. Pierce
  • Xiao Ou Shu
  • Bette J. Caan
Epidemiology

DOI: 10.1007/s10549-011-1914-3

Cite this article as:
Kwan, M.L., Chen, W.Y., Kroenke, C.H. et al. Breast Cancer Res Treat (2012) 132: 729. doi:10.1007/s10549-011-1914-3

Abstract

Obese and underweight women who develop breast cancer may have poorer survival compared with normal-weight women. However, the optimal weight for best prognosis is still under study. We conducted a prospective investigation of pre-diagnosis body mass index (BMI) and mortality among 14,948 breast cancer patients in the After Breast Cancer Pooling Project. Breast cancer patients diagnosed from 1990 to 2006 with AJCC Stage I–III breast tumors were drawn from four prospective cohorts. Hazard ratios (HR) and 95% confidence intervals (CI) representing the associations of BMI categories (World Health Organization international classifications) with recurrence and mortality were estimated using delayed entry Cox proportional hazards models. Obese (30 to <35 kg/m2), severely obese (35 to <40 kg/m2), and morbidly obese (≥40 kg/m2) were examined. After a mean follow-up of 7.8 years, 2,140 deaths and 2,065 recurrences were documented. Both underweight (HR = 1.59; 95% CI: 1.18, 2.13) and morbidly obese women (HR = 1.81; 95% CI: 1.42, 2.32) had the greatest risk of overall mortality compared with normal weight (18.5–24.9 kg/m2) women. Severe obesity (HR = 1.09; 95% CI: 0.88, 1.36) and obesity (HR = 1.11; 95% CI: 0.97, 1.27) were related to small non-significant increased risks. Overweight (25.0–29.9 kg/m2) was not associated with any excess risk compared with normal weight. Similar associations were found for breast cancer death and non-breast cancer death but not recurrence. Women who were underweight and morbidly obese before breast cancer diagnosis were at the greatest risk of all-cause mortality. Morbidly obese women were also at increased risk of death from breast cancer. These results suggest that degree of obesity confers differential risk on survival.

Keywords

Body mass indexWeightObesityBreast cancerSurvivalPrognosisMortality

Abbreviations

ABCPP

After Breast Cancer Pooling Project

SBCSS

Shanghai Breast Cancer Survival Study

LACE

Life After Cancer Epidemiology

WHEL

Women’s Healthy Eating and Living

NHS

Nurses’ Health Study

KPNC

Kaiser Permanente Northern California

IRB

Institutional review board

BMI

Body mass index

MET

Metabolic equivalents

MI

Myocardial infarction

ER

Estrogen receptor

PR

Progesterone receptor

HR

Hazard ratio

CI

Confidence interval

Copyright information

© Springer Science+Business Media, LLC. 2011

Authors and Affiliations

  • Marilyn L. Kwan
    • 1
  • Wendy Y. Chen
    • 2
    • 3
  • Candyce H. Kroenke
    • 1
  • Erin K. Weltzien
    • 1
  • Jeannette M. Beasley
    • 4
  • Sarah J. Nechuta
    • 5
  • Elizabeth M. Poole
    • 2
  • Wei Lu
    • 6
  • Michelle D. Holmes
    • 2
  • Charles P. QuesenberryJr.
    • 1
  • John P. Pierce
    • 7
  • Xiao Ou Shu
    • 5
  • Bette J. Caan
    • 1
  1. 1.Division of ResearchKaiser PermanenteOaklandUSA
  2. 2.Channing Laboratory, Department of MedicineBrigham and Women’s Hospital and Harvard Medical SchoolBostonUSA
  3. 3.Department of Medical OncologyDana-Farber Cancer InstituteBostonUSA
  4. 4.Fred Hutchinson Cancer Research CenterSeattleUSA
  5. 5.Division of Epidemiology, Department of MedicineVanderbilt University School of MedicineNashvilleUSA
  6. 6.Shanghai Institute for Preventive MedicineShanghaiChina
  7. 7.Cancer Prevention and Control Program, Moores UCSD Cancer CenterUniversity of California, San DiegoSan DiegoUSA