Obesity, Through Analysis of Body Mass Index and Waist-Hip Ratio as a Risk Factor for Breast Cancer: A Case-Control Study

Abstract

INTRODUCTION: Breast cancer represents a serious public health problem worldwide, for its high incidence, morbidity, mortality, especially among women. It’s a multifactorial disease and the role of obesity in the etiology of breast cancer is found mainly in postmenopausal women in whom the increase in body weight and changes in fat distribution are common. MATERIALS AND METHODS: It is a multi-institutional case-control study. We studied 703 women, 268 of these were the case group and 435 represented the control group for subsequent evaluation of selected risk factors in one year from August 2009 to 2010. Data collection was performed by applying a protocol and an informed consent approved by the ethics committee of Federal University of Alagoas. All patients were weighed and measured for height and waist and hip circumferences. Data were entered and analyzed by Epi-Info 3.5.1. Windows version. Statistical tests were: Chi-square test, Bartlett s test, ANOVA and Mann-Whitney/Wilcoxon (Kruskal-Wallis test for two groups). RESULTS: The mean age of women with cancer was 52.40 years. of the 325 (46.2%) patients who were in menopause 157 (48.3%) were carriers of breast cancer and 168 (51.7%) were healthy. Among the 378 (58.3%) in premenopausal patients, 111 (29.4%) belonged to the case group and 267 (70.6%) to the control group. (OD: 2.2479, 95% CI, 1.6481 to 3.066). The body mass index (BMI) didn’t show any significant relationship between cases and controls (p = 0.9713). The waist-hip ratio (WHR) showed an average of 0.9295 in the case patients and average less than 0.8714 in the control patients (p = 0.0000). DISCUSSION: The incidence of breast cancer increases rapidly with age. The average age of the patients with breast cancer was 52.40 years. Among controls the mean age was 46.78 years. The results showed BMI of postmenopausal women with an average of 26.15 kg/m2 and an average of 25.65 kg/m2 in women in reproductive age (p = 0.0136). The excessive body weight is associated with increased risk of breast cancer in postmenopausal women. In contrast, excess weight does not seem to be associated or even often associated with a lower risk of cancer in premenopausal women. In our study we observed no statistically significant difference in BMI between cases and controls (p = 0.9887), which agrees with other results already described in the literature. It is noteworthy that the incidence of obesity and/or breast cancer in the populations studied may have influenced the results. The mean WHR found among all patients was 0.89. The mean WHR in patients with breast cancer was higher (0.92) compared to controls (0.87) (p: 0.000). The combination of higher ratio circumference and WHR with the incidence of breast cancer portrayed in this study agrees with the studies conducted to investigate this same variable as a risk factor for breast cancer. Considering menopausal status, patients in reproductive age had resulted in a mean waist-hip ratio of 0.87 and an average of 0.91 menopausal (P: 0.000). Significant result and it also represents what is found in other studies. CONCLUSION: For menopausal status, it was found that to be in menopause was a risk factor for breast cancer. The BMI did not show statistical significance for cancer and waist-hip ratio had its association with proven cases of cancer.