Obesity, mammography use and accuracy, and advanced breast cancer risk

Abstract

Background: Being overweight or obese is associated with increased breast cancer risk and disease severity among postmenopausal women, but whether extent of mammography use and accuracy modify this association and further contribute to increases in disease severity at diagnosis among overweight and obese women is unclear. Methods: We prospectively collected data during 1996-2005 on 287 115 postmenopausal women not using hormone therapy (HT) who underwent 614 562 mammography examinations; 4446 women were diagnosed with breast cancer within 12 months of a mammography examination. We calculated rates per 1000 mammography examinations of large (>15 mm), advanced-stage (IIb, III, or IV), high-grade (3 or 4), estrogen receptor (ER)-positive and -negative, and screen-detected and non-screen-detected breast cancer across body mass index (BMI, kg/m 2) groups defined as normal (18.5-24.9), overweight (25.0-29.9), obese class I (30.0-34.9), and obese class II/III (≥35.0), adjusting for age, race/ethnicity, and mammography registry and use. All statistical tests were two-sided. Results: Adjusted rates per 1000 mammography examinations of overall breast cancer increased across BMI groups (6.6 normal, 7.4 overweight, 7.9 obese I, 8.5 obese II/III; Ptrend