Sarcopenia, obesidade sarcopênica e densidade mineral óssea em mulheres recém-diagnosticadas com câncer de mama: estudo caso-controle

Abstract

Introduction: Breast cancer is the most prevalent neoplasm among women and has multicausal risk factors. In this sense, the relationship between breast cancer and different body components needs to be better investigated. Objective: Evaluate associations between sarcopenia, sarcopenic obesity and bone mineral density (BMD) considering the menopausal status in women recently diagnosed with breast cancer. Methodology: This is a case-control study conducted in a reference Center in the Mid-West region of Brazil, during August/2014 and September/2017. The dissertation was divided into two articles. The first one, it was conducted with 175 cases of breast cancer and 299 controls about sarcopenia and sarcopenic obesity, and the second, about BMD, having 142 cases and 234 controls. For both, the volunteers were matched by age (±5 years), body mass index (BMI) and menopausal status (pre and postmenopausal). A standardized and pre-tested questionnaire was used for data collection and the body composition was measured using dual energy X-ray absorptiometry (DXA) method. Sarcopenia was identified by relative skeletal muscle index (RSMI) and sarcopenic obesity by percentage of body fat, it was estimated the BMD of the sites: lumbar spine, femoral neck and total femur. The database was structured in double-entry and the statistical analysis was performed by the software SPSS version 23. The results were presented with the total sample and considering the menopausal status. The comparisons of differences of the means between cases and controls were done by a Mann-Whitneu test, for the categorical variables it was run a chi-square of Pearson or Fisher exact test. Odds Ratio was used for measure associations using logistic regression, the significance level adopted was 5% and the 95% as confidence interval. The cut-off point for some variables was estimated by the point of encounter between sensitivity and specificity of the ROC curve with significant area (p <0.05). Results: Sarcopenia and sarcopenic obesity were not associated with a greater chance of developing breast cancer, however, the reduced manual grip strength (OR = 2.43 [1.10-5.40]; OR = 2.72 [1.25-5.92], respectively) and slow gait velocity (OR = 2.46 [1.45-4.18]); OR = 2.38 [1.40-4.03], respectively), which are predictors of sarcopenia, were. Women from the total sample allocated in the highest quartile of lumbar spine BMD had a 2.31-fold greater chance of developing breast cancer (OR = 2.31, 1.02-5.25, p = 0.045) after adjusting for variables of confusion. Conclusion: Sarcopenia and sarcopenic obesity were not associated with breast cancer, however, variables that are related to both conditions, reduced hand grip strength and slow gait, were significant. In addition, the high lumbar spine BMD was positively associated with breast carcinogenesis in the total sample.