title: Investigative clinical study on prostate cancer part IV: exploring functional relationships of total testosterone predicting free testosterone and total prostate-specific antigen in operated prostate cancer patients.
abstract: OBJECTIVE
  To explore, in operated prostate cancer patients, functional relationships of total testosterone (tt) predicting free testosterone (ft) and total PSA.
  
  
  METHODS
  128 operated prostate cancer patients were simultaneously investigated for tt, ft and PSA before surgery. Patients were not receiving 5α-reductase inhibitors, LH-releasing hormone analogues and testosterone replacement treatment. Scatter plots including ft and PSA versus tt were computed in order to assess the functional relationship of the variables. Linear regression analysis of tt predicting ft and PSA was computed.
  
  
  RESULTS
  tt was a significant predictor of the response variable (ft) and different subsets of the patient population were assessed according to the ft to tt ratio. PSA was related to tt according to a nonlinear law. tt was a significant predictor of PSA according to an inversely nonlinear law and different significant clusters of the patient population were assessed according to the different constant of proportionality computed from experimental data.
  
  
  CONCLUSIONS
  In our prostate cancer population, ft was significantly predicted by tt according to a linear law, and the ft/tt ratio was a significant parameter for assessing the different clusters. Also, tt was a significant variable predicting PSA by a nonlinear law and different clusters of the patient population were assessed by the different constants of proportionality. As a theory, we explain the nonlinear relation of tt in predicting PSA as follows: (a) the number of androgen-independent prostate cancer cells increases as tumor volume and PSA serum levels rise, (b) the prevalence of androgen-independent cells producing a substance which inhibits serum LH, and (c) as a result lower levels of serum tt are detected.
authors.affiliation: Department of Urology, Azienda Ospedaliera Universitaria Integrata, Ospedale Civile Maggiore, Verona, Italy. drporcaro@yahoo.com
authors.forename: Antonio B
authors.initials: AB
authors.lastname: Porcaro
authors.forename: Aldo
authors.initials: A
authors.lastname: Petrozziello
authors.forename: Filippo
authors.initials: F
authors.lastname: Migliorini
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Lacola
authors.forename: Mario
authors.initials: M
authors.lastname: Romano
authors.forename: Teodoro
authors.initials: T
authors.lastname: Sava
authors.forename: Claudio
authors.initials: C
authors.lastname: Ghimenton
authors.forename: Beatrice
authors.initials: B
authors.lastname: Caruso
authors.forename: Stefano
authors.initials: S
authors.lastname: Zecchini Antoniolli
authors.forename: Emanuele
authors.initials: E
authors.lastname: Rubilotta
authors.forename: Carmelo
authors.initials: C
authors.lastname: Monaco
authors.forename: Luigi
authors.initials: L
authors.lastname: Comunale
mesh_terms: D000368:Aged; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008495:Medical Oncology / Q000379:methods; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000473:pathology*; D012044:Regression Analysis; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D007986:Luteinizing Hormone; D017430:Prostate-Specific Antigen