[Influence of obesity on clinicopathological characteristics in patients with clinically localized prostate cancer]

Abstract

Objective: To investigate the influence of anthropometric measures of obesity, including body mass index (BMI), abdominal subcutaneous adipose tissue and visceral adipose tissue, on pathological characteristics in patients with clinically localized prostate cancer.

Methods: From January 2006 to March 2013, the 413 patients of prostate cancer who received radical prostatectomy (RP) and their clinical and pathological data had been collected. The median age for the entire cohort was 68 years, which ranged from 48 to 78 years. All patients were diagnosed with prostate cancer before surgery and the Gleason score ranged from 4 to 10 (median 7). Anthropometric measures of abdominal adiposity including anterior abdominal fat, posterior abdominal fat and anteroposterior diameter were measured from the T2 weighted sagittal localization images of MRI scans and subcutaneous adipose tissue and the percentage of visceral adipose tissue were calculated. The patients' clinical and pathologic characteristics across BMI groups were compared used Student's t test for continuous variables or chi-squared test for categorical variables. Moreover, univariable and multivariable logistic regression models were used to address the influence of anthropometric measures of obesity on pathological outcomes.

Results: The BMI ranged from 14.2 to 34.0 kg/m(2) and the median value was 23.8 kg/m(2). The abdominal subcutaneous adipose tissue ranged from 12.6 to 60.3 mm and the median value was 31.4 mm. The percentage of visceral adipose tissue ranged from 71.1% to 92.1% and the median value was 83.8%. In RP specimens, Gleason score ≥ 8 was observed in 141 patients (34.1%), pathological tumor stage was T3a in 69 patients (16.7%) and pathological tumor stage was T3b in 78 patients (18.9%). Positive surgical margin and lymph node involvement were observed in 71(17.2%) and 38(9.2%) patients, respectively. Although univariate analysis showed that BMI ≥ 25 kg/m(2) was associated with pathological Gleason score ≥ 8 (OR = 1.413, P = 0.035), this positive correlation disappeared in multivariate analysis(P = 0.095). In multivariate analysis, the percentage of visceral adipose tissue was significantly associated with pathological Gleason score (OR = 9.618, P = 0.000), extracapsular extension (OR = 6.750, P = 0.002) and seminal vesicle invasion (OR = 4.419, P = 0.007) after adjusting for patient age, PSA level, clinical stage and biopsy Gleason score.

Conclusions: Anthropometric measures of abdominal adiposity was more sophisticated than simple BMI to evaluate the risk of obesity with regard to the aggressiveness of prostate cancer. The percentage of visceral adipose tissue was an independent factor for pathological Gleason score, extracapsular extension and seminal vesicle invasion in RP specimens.