Investigative clinical study on prostate cancer part VII: prolactin and the pituitary-testis-prostate axis at the time of initial diagnosis and subsequent cluster selection of the patient population.

AIM: To evaluate prolactin (PRL) physiopathology along the pituitary-testis-prostate axis at the time of initial diagnosis of prostate cancer in relation to the available clinical variables and to the subsequent cluster selection of the patient population. PATIENTS AND METHODS: The study involved 100 individuals diagnosed with prostate cancer. Age, percentage of positive cores at transrectal ultrasound scan biopsy (P+), biopsy Gleason score (BGS), PRL, luteinizing hormone (LH), follicle stimulating hormone (FSH), total testosterone (TT), free testosterone (FT) and prostate-specific antigen (PSA) were the continuous clinical variables. All patients had histologically proven carcinoma of the prostate and had not previously received hormonal manipulations. Correlation and multiple linear regression analysis of the the variables along the pituitary-testis-prostate cancer axis was performed. The prostate cancer population was clustered according to the PRL/P+ ratio into group A (4.20≤PRL/P+ ≤20), B (20<PRL/P+ ≤44) and C (44<PRL/P+≤157.83). Correlation, multiple linear regression and analysis of variance of the clustered population along the pituitary-testis-prostate cancer axis was computed. RESULTS: At diagnosis of prostate cancer, pituitary hormones were significantly correlated to FT (PRL, FSH, LH) and to PSA (FSH, LH); also close to significance was the correlation of both PRL and LH to P+ (p=0.07). On multiple linear regression analysis only, PRL was independently predicted by P+ (p=0.02), while PSA independently predicted both FSH (p=0.03) and LH (p=0.01). PRL was significantly correlated to P+ in the prostate cancer population clustered according to the PRL/P+ ratio into groups A, B and C which significantly differed for PRL (p=0.002), P+ (p<0.0001) and BGs (p=0.0001). CONCLUSION: In the prostate cancer population at diagnosis and along the pituitary-testis-prostate axis, PRL is significantly correlated to P+; moreover, PRL is also independently predicted by P+. Because of the high correlation between PRL and P+, the prostate cancer population at diagnosis might be clustered according to the PRL/P+ ratio into groups A, B and C, which, as a theory, might express prognostic potential for clinical applications. However, confirmatory studies are needed.