title: Pretreatment tumor volume estimation based on total serum psa in patients with localized prostate cancer.
abstract: OBJECTIVE
  To establish a formula that estimates tumor volume in localized prostate cancer based on serum prostate specific antigen levels. One of the main prognostic variables in localized prostate cancer is tumor volume, which can be precisely defined only after prostate extirpation. The present study defines a simple method that allows for estimation of tumor volume before treatment, which can help to establish a better therapeutic strategy for each patient.
  
  
  METHODS
  From 1997 to 2002, 735 patients with prostate cancer of stagesT1c-T2c without any previous treatment were submitted to radical prostatectomy. Surgical specimens were evaluated by the same pathologist and the total tumor volume (in cc) and the relative tumor volume (as the percent of the total prostate volume) were determined using the grid morphometric method. Pretreatment serum prostate specific antigen was correlated with tumor volume in each patient using a linear regression model.
  
  
  RESULTS
  There were positive correlations between the serum levels of prostate specific antigen and the total tumor volume in cc (p<0.001) and the relative tumor volume as a percentage (p<0.001). For each ng/ml unit increment of serum prostate specific antigen, there was a 0.302 cc increase in total tumor volume and a 0.7% increase in relative tumor volume. Total and percent tumor volume could be calculated, respectively, using the formulas Volume (cc) = 3.476 + 0.302 x PSA (ng/ml) and Volume (%) = 11.331 + 0.704 x prostate specific antigen (ng/ml).
  
  
  CONCLUSIONS
  Tumor volume in patients with prostate cancer can be determined before treatment based on the serum prostate specific antigen levels.
authors.affiliation: Division of Urology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil. kato_med91@yahoo.com.br
authors.forename: Raphael Barroso
authors.initials: RB
authors.lastname: Kato
authors.forename: Victor
authors.initials: V
authors.lastname: Srougi
authors.forename: Fernanda Aburesi
authors.initials: FA
authors.lastname: Salvadori
authors.forename: Pedro Paulo Marino Rodrigues
authors.initials: PP
authors.lastname: Ayres
authors.forename: Katia Moreira
authors.initials: KM
authors.lastname: Leite
authors.forename: Miguel
authors.initials: M
authors.lastname: Srougi
mesh_terms: D000230:Adenocarcinoma / Q000097:blood* / Q000473:pathology / Q000601:surgery; D000328:Adult; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000601:surgery; D012044:Regression Analysis; D012189:Retrospective Studies
chemical_list: D017430:Prostate-Specific Antigen