Preliminary investigation of brown adipose tissue assessed by PET/CT and cancer activity

Objective: To determine the role of brown adipose tissue (BAT) in cancer activity. Materials and methods: The study group comprised 142 patients (121 female, 21 male; mean age, 49 ± 16 years) who underwent F18-FDG PET/CT (PET/CT) for staging or surveillance of cancer and who were BAT-positive on PET/CT. BAT volume by PET/CT, abdominal (visceral and subcutaneous) fat and paraspinous muscle cross-sectional areas (CSA) were assessed. Groups with and without active cancer on PET/CT were compared using a two-sided paired t test. Linear regression analyses between BAT and body composition parameters were performed. Results: There were 62 patients (54 female, eight male) who had active cancer on PET/CT and 80 patients (67 female, 13 male) without active cancer. Groups were similar in age and BMI (p ≥ 0.4), abdominal fat and muscle CSA, fasting glucose, and outside temperature at time of scan (p ≥ 0.2). Patients who had active cancer on PET/CT had higher BAT volume compared to patients without active cancer (p = 0.009). In patients without active cancer, BAT was positively associated with BMI and abdominal fat depots (r = 0.46 to r = 0.59, p < 0.0001) while there were no such associations in patients with active cancer (p ≥ 0.1). No associations between BAT and age or muscle CSA were found (p ≥ 0.1). Conclusions: BAT activity is greater in patients with active cancer compared to age-, sex-, and BMI-matched BAT-positive patients without active cancer, suggesting a possible role of BAT in cancer activity.