title: Body mass index adjusted prostate-specific antigen and its application for prostate cancer screening.
abstract: OBJECTIVE
  The prostate cancer prevention trial (PCPT) prostate cancer risk calculator was developed to aid physicians in counseling men for consideration of prostate biopsy based on prostate-specific antigen (PSA) and other clinical risk factors. This study investigated the role of body mass index (BMI) in this assessment.
  
  
  METHODS
  BMI category was defined as < 25 (under/normal weight), 25.0-29.9 (overweight), 30.0-34.9 (obese [OB] I), 35.0-39.9 (OB II), and ≥ 40 (OB III). BMI-adjusted PSA for a man was determined by multiplying his PSA to the ratio of the geometrical mean of PSA for BMI < 25 to the geometrical mean of PSA for his BMI category. Operating characteristics of PSA and BMI-adjusted PSA were compared with PCPT risks using area underneath the receiver operating characteristic curve (AUC). Statistical tests of differences between AUCs for different diagnostic tests were performed with the nonparametric U-statistic method.
  
  
  RESULTS
  BMI-adjusted PSA equaled to unadjusted PSA multiplying 1.09, 1.20, 1.50, and 1.71 for men in overweight, OBI, OBII, and OBIII categories, respectively. The AUC for BMI-adjusted PSA values (0.84) did not differ from PSA; that of the PCPT calculator with BMI-adjusted PSA (0.87) did not differ from the calculator with PSA. Of 2816 men with a PSA less than or equal to 2.5 ng/mL who did not undergo biopsy, 126 (4.5%) would have a BMI-adjusted PSA exceeding 2.5 ng/mL.
  
  
  CONCLUSIONS
  Because of lower levels of PSA, overweight and obese men may have diminished cancer detection opportunities when undergoing PSA-based screening.
authors.affiliation: Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA. liangy@uthscsa.edu
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Liang
authors.forename: Donna P
authors.initials: DP
authors.lastname: Ankerst
authors.forename: Michael
authors.initials: M
authors.lastname: Sanchez
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Leach
authors.forename: Ian M
authors.initials: IM
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D051517:Digital Rectal Examination; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D017430:Prostate-Specific Antigen