Correlation between BMI and the pathological features of prostate cancer at biopsy

Introduction/Aim: Numerous clinical trials investigated the association between obesity and prostate cancer, but they yielded inconsistent results (1). Obesity has been found to be related to prostatic tumors at more advanced stages and higher Gleason grade when compared with normal population (2). An increased number of biopsy cores has been advocated by some Authors in obese and overweight men due to an increased difficulty and delay in cancer detection (3). The main aim of our research was to correlate Body Mass Index (BMI) with the pathological characteristics of prostate cancer at biopsy. Patients and Methods: Patients with positive prostate biopsy performed for palpable prostate nodule and/or elevated PSA levels were considered in the present study. A transrectal prostate biopsy procedure, not less than 12 cores, was performed. The number of specimens was increased in case of re-biopsy (18-24 cores or more). After informed consent, a database has been created, including clinical and pathological data: demographics, PSA, digital rectal examination, transrectal ultrasound and prostate cancer features at biopsy. Patients were divided into four categories according to their BMI as follows: 16-19,9 (underweight), 20.0-24.9 (normal weight), 25.0-29.9 (overweight) and ≥30.0 (obese). The statistical analysis was conducted with Fisher’s exact test for Gleason pattern 4 (<4 or ≥4) and BMI for single weight class and the Pearson’s Chisquared test with Yates’ continuity correction for aggregate BMI classes. Results: Out of 149 patients diagnosed with prostate cancer, the Gleason score was available for 121 (81.2%), ASAP or PIN were found in 5 more patients (3.4%). Twenty-seven (21.4%) patients had a previous negative biopsy. The median age was 71 years (range 45-86). The median BMI was 26.7 kg/m2 (range 17.5-37.4). Two patients (1.3%) were underweight, 43 (28,6%)patients had normal weight (median BMI 23), 70 (47%) were overweight (median BMI 26.8) and 34 (22.8%) were obese (median BMI 35.3). Median PSA was 9.5 ng/ml (range 0,41- 1339). A prostate nodule was palpable in 45 (30.2%) patients. The median prostate volume was 44.5 cc. A Gleason pattern of 4 or more was evident in 49 (40.5%) patients, while it was not detected in the remaining 72 (59.5%) patients. The presence of Gleason pattern 4 did not result in relation to the class of BMI (p-value=0.9814), neither combining different classes: normal weight and overweight men versus obese ones (p-value=0.7696); normal weight versus overweight and obese men (p-value=0.9678). Discussion and Conclusion: Our study, in contrast with some evidence in literature, did not show any significant correlation between BMI and the presence of Gleason pattern 4. However, the small number of patients did not allow to include in our analysis important factors, such as biological, hormonal, environmental and life-style factors, involved in the pathogenesis of prostate cancer. A larger, prospective, multicenter investigation is on going. References 1 Howlader N, Krapcho M, Neyman N et al: SEER Cancer statistics review, 1975-2008. National Cancer Institute, Bethesda,http://seer.cancer.gov/csr/1975_2008/, based on November 2010 SEER data submission. 2 Nunzio CD, Freedland S, Miano L, Agrò EF, Bañez L and Tubaro A: The uncertain relationship between obesity and prostate cancer: an Italian biopsy cohort analysis. European Journal of Surgical Oncology 37(12): 1025-1029, 2011. 3 Wallner LP, Morgenstern H, McGree ME et al: The effects of body mass index on changes in prostate-specific antigen levels and prostate volume over 15 years of follow-up: implications for prostate cancer detection. Cancer Epidemiol Biomarkers Prev 20(3): 501-508, 2011. Doi: 10.1158/1055-9965. EPI-10-1006. Epub 2011 Jan 17. 3.