Abstract
BACKGROUND: There is limited understanding about why sarcopenia is happening in bladder cancer, and which modifiable and nonmodifiable patient-level factors affect its occurrence. OBJECTIVE: The objective is to determine the extent to which nonmodifiable risk factors, modifiable lifestyle risk factors, or cancer-related factors are determining body composition changes and sarcopenia in bladder cancer survivors. DESIGN, SETTING, AND PARTICIPANTS: Patients above 18 yr of age with a histologically confirmed diagnosis of bladder cancer and a history of receiving care at Duke University Medical Center between January 1, 1996 and June 30, 2017 were included in this study. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Bladder cancer survivors from our institution were assessed for their dietary intake patterns utilizing the Diet History Questionnaire II (DHQ-II) and physical activity utilizing the International Physical Activity Questionnaire long form (IPAQ-L) tools. Healthy Eating Index 2010 (HEI2010) scores were calculated from DHQ-II results. Body composition was evaluated using Slice-O-Matic computed tomography scan image analysis at L3 level and the skeletal muscle index (SMI) calculated by three independent raters. RESULTS AND LIMITATIONS: A total of 285 patients were evaluated in the study, and the intraclass correlation for smooth muscle area was 0.97 (95% confidence interval: 0.94-0.98) between raters. The proportions of patients who met the definition of sarcopenia were 72% for men and 55% of women. Univariate linear regression analysis demonstrated that older age, male gender, and black race were highly significant predictors of SMI, whereas tumor stage and grade, chemotherapy, and surgical procedures were not predictors of SMI. Multivariate linear regression analysis demonstrated that modifiable lifestyle factors, including total physical activity (p=0.830), strenuousness (high, moderate, and low) of physical activity (p=0.874), individual nutritional components (daily calories, p=0.739; fat, p=0.259; carbohydrates, p=0.983; and protein, p=0.341), and HEI2010 diet quality (p=0.822) were not associated with SMI. CONCLUSIONS: Lifestyle factors including diet quality and physical activity are not associated with SMI and therefore appear to have limited impact on sarcopenia. Sarcopenia may largely be affected by nonmodifiable risk factors. PATIENT SUMMARY: In this report, we aim to determine whether lifestyle factors such as diet and physical activity were the primary drivers of body composition changes and sarcopenia in bladder cancer survivors. We found that lifestyle factors including dietary habits, individual nutritional components, and physical activity do not demonstrate an association with skeletal muscle mass, and therefore may have limited impact on sarcopenia.