Obesity and mammography: a systematic review and meta-analysis

Abstract

Background: Obese women experience higher postmenopausal breast cancer risk, morbidity, and mortality and may be less likely to undergo mammography.

Objectives: To quantify the relationship between body weight and mammography in white and black women.

Data sources and review methods: We identified original articles evaluating the relationship between weight and mammography in the United States through electronic and manual searching using terms for breast cancer screening, breast cancer, and body weight. We excluded studies in special populations (e.g., HIV-positive patients) or not written in English. Citations and abstracts were reviewed independently. We abstracted data sequentially and quality information independently.

Results: Of 5,047 citations, we included 17 studies in our systematic review. Sixteen studies used self-reported body mass index (BMI) and excluded women <40 years of age. Using random-effects models for the six nationally representative studies using standard BMI categories, the combined odds ratios (95% CI) for mammography in the past 2 years were 1.01 (0.95 to 1.08), 0.93 (0.83 to 1.05), 0.90 (0.78 to 1.04), and 0.79 (0.68 to 0.92) for overweight (25-29.9 kg/m(2)), class I (30-34.9 kg/m(2)), class II (35-39.9 kg/m(2)), and class III (> or =40 kg/m(2)) obese women, respectively, compared to normal-weight women. Results were consistent when all available studies were included. The inverse association was found in white, but not black, women in the three studies with results stratified by race.

Conclusions: Morbidly obese women are significantly less likely to report recent mammography. This relationship appears stronger in white women. Lower screening rates may partly explain the higher breast cancer mortality in morbidly obese women.

Figure 1

Study flow diagram. *Search terms for breast cancer, cervical cancer, colon cancer, body weight, breast cancer screening, cervical cancer screening, and colon cancer screening were used to conduct the search of electronic databases. Specific terms are provided in Appendix Table 5. ^†Manual searching involved searching of references of included and key articles and searching of tables of contents of the following journals: Cancer, Journal of General Internal Medicine, Annals of Internal Medicine, Obesity, Ethnicity and Disease, Cancer Detection and Prevention, Journal of Health Care for the Poor and Underserved, Preventing Chronic Disease, Journal of Women’s Health, American Journal of Public Health, Preventive Medicine, and American Journal of Epidemiology. ^‡Reasons for exclusion add up to more than abstracts or articles excluded since reviewers could have more than one reason for exclusion. ^§Studies included in the main meta-analysis reported nationally-representative results in five standard body mass index categories (normal 18–24.9 kg/m², overweight 25–29.9 kg/m², class I obesity 30–34.9 kg/m², class II obesity 35–39.9 kg/m², class III obesity ≥ 40 kg/m²). A seventh study met these criteria, but was based on the same data as another study and therefore was only included in a sensitivity analysis. ^║Studies included in the race-specific meta-analysis reported nationally representative results in five standard body mass index categories (normal 18–24.9 kg/m², overweight 25–29.9 kg/m², class I obesity 30–34.9 kg/m², class II obesity 35–39.9 kg/m², class III obesity ≥40 kg/m²).

Figure 2

Meta-analyses of nationally representative studies with BMI in five categories. Note: Included studies:–,,; BMI categories: overweight 25–29.9 kg/m², class I obesity 30–34.9 kg/m², class II obesity 35–39.9 kg/m², class III obesity ≥40 kg/m². *Data from analysis of white women. ^**Data from analysis of black women. BMI, body mass index; OR, odds ratio; CI, confidence interval.