The Clinical Application Of Serum PSA And Its Relevant Indexes In Diagnosing Prostate Cancer

Objective:To explore the clinical application of serum total prostate specific antigen(tPSA),free porstate specific antigen(fPSA)/tPSA and tPSA/body mass index(BMI) ratio in the diagnosis of prostate cancer(PCa).The association of serum PSA and BMI is studied in PCa group.To evaluate the correlation of age,BMI, prostatic volume(PV) and pathological grade on serum tPSA level of PCa patients.Methods:The study participants were recruited from the First Affiliate Hospital of Jinan University from May 2006 to March 2008.All patients had been the first diagnosed by pathologic examination.There were 61 cases of PCa,90 cases of BPH. The levels of serum tPSA and fPSA were detected in two groups.To collect height,weight and age of all patients.PV was measured by transabdominal ultrasonography. The value of BMI was calculated.The ratios of fPSA/tPSA and tPSA/BMI were calculated.Wilcoxon rank sum test was used to compare different statistical value in two groups.Using the receptive operator character(ROC) curve to analyze the predict value of tPSA/BMI ratio in diagnosis of PCa.By using Spearman rank correlation analysis,the correlation between pathological grade and BMI was analyzed in PCa group;the correlation among tPSA,age,BMI and PV was analyzed and using multiple liner regression to exclude influencing factor.Results:1.The detected PSA value and its indexes were significant statistical difference between PCa group and BPH group(P＜0.05),whereas value of PV was not significant statistical difference in two groups.2.The tPSA/BMI ratio was significantly different between patients with PCa and BPH group(z=-7.611, P=-0.000),from the ROC curve we can find that when tPSA/BMI ratio was 0.5,its sensitivity,specificity,negative predictive value and positive predictive value were 80.33%,81.11%,85.88%and 74.24%respectively.When f/tPSA ratio was taken at a threshold of 0.15,its sensitivity,specificity,negative predictive value and positive predictive value were lower than that of tPSA/BMI ratio.3.There were 41 cases (67.21%) in PCa group with tPSA/BMI ratio more than 23kg/m~2,adversely 23 cases (32.79%) in PCa group.4.There were not significant and correlation among age,PV and tPSA in PCa group,but there was significant inverse correlation between BMI and tPSA in PCa group(It's Spearman correlation coefficient r=-0.295,P=0.021); Pathological grade correlated positively with serum tPSA and related negatively with BMI(It's Spearman correlation coefficient 0.319,-0.260,respectively;P=0.012 0.043 respectively).We used stepwise multiple linear regression to evaluate the impact of age,BMI and volume on serum tPSA,which concluded that the factor of age and PV can be excluded.In BPH group,there was positive relation between tPSA and PV(It's Spearman correlation coefficient r=0.344,P=-0.001).There was not significant correlation between age and BMI.Conclusions:1.The tPSA/BMI ratio is a useful diagnostic indicator for PCa screening.When tPSA/BMI ratio was 0.5,the best values of sensitivity and specificity were obtained where serum tPSA value was more than 10ng/ml.2.There is inverse significant association between PSA and BMI in PCa group.There is positive significant association between pathological grade and BMI in PCa group.3.The level of serum PSA is not affected by age and PV in PCa group.There is significant correlation between PSA and PV in BPH group.The level of serum PSA will increase with the enlargement of PV.