Correlation Analysis Of Positive Surgical Margin After Robot-assisted Radical Prostatectomy And Intravesical Prostatic Protrusion Through Different Imaging And Evaluation Of The Model Effectiveness

Research background and purpose:With the continuous development of robot surgery,robot-assisted laparoscopic radical prostatectomy(RARP)has been widely used in China.Intravesical prostatic protrusion(IPP)is a kind of common imaging feature in clinical work,but its influence on the therapeutic effect after RARP has been controversial.Positive surgical margin(PSM)after RARP is a pathological feature of poor prognosis,and reducing the positive rate of surgical margin is the goal pursued by urologists.In order to further explore the correlation between IPP and positive surgical margin after RARP,and to lay a solid foundation for the establishment of a further predictive model,we adopted the model of interdisciplinary cooperation among medicine,imaging,pathology and computer science,and used univariate analysis and logistic multivariate regression analysis to explore the correlation between some factors,such as IPP measured by MRI or CT,with apical and basal positive surgical margin after RARP.The performance of the logistic regression model of positive surgical margin was simply evaluated.Data and Methods:The clinical data of 352 patients who underwent RARP in Sichuan Provincial People’s Hospital from March 2017 to November 2021 were analyzed retrospectively,including age,surgical methods,prostate specific antigen(PSA),biopsy Gleason score,International Society of Urological Pathology(ISUP)grade,clinical TNM stage,prostate specific antigen density(PSAD),MRI and CT imaging features(prostate volume,intravesical protrusion of prostate length(IPPL),circumference of bladder neck).The patients were divided into CT group and MRI group according to the different imaging examination in our hospital before surgery.All patients underwent RARP,and three different surgical approaches were used,which were extraperitoneal approach via PORT,modified extraperitoneal single incision approach and transperitoneal approach.The status of surgical margin and the position of positive surgical margin were recorded after surgery.Univariate analysis was conducted withχ~2test,Mann-Whitney U test and t-test.The variables with P<0.1 in univariate analysis were included in logistic multivariate regression analysis.The alignment diagrams of the established logistic regression models were drawn and the effectiveness of the established logistic regression models was simply evaluated.The difference is statistically significant when P<0.05.Result:1.There are 338 patients in the MRI group.68 cases(20.1%)have basal positive surgical margin and 90 cases(26.6%)have apical positive surgical margin,with an age of(70.414±7.418)years old.There are 106 cases of extraperitoneal approach via PORT,117 cases of modified extraperitoneal approach and 115 cases of transperitoneal approach.Preoperative median PSA is14.32(8.62,19.433)ng/ml,in which PSA<10,10-20 and>20ng/ml are102,163and 73 cases respectively.The median prostate volume is45.2(32.192,62.197)ml,of which 75,130 and 133 cases are<30,30-50 and>50ml respectively.The preoperative ISUP grade 1,2,3,4 and 5 have 50,68,93,60 and 67 cases respectively.Clinical T stage T1-2 has 234 cases,T3-4 stage has 104 cases.Median PSAD is 0.324(0.178,0.668)ng/ml~2.Circumference of bladder neck is(110.249±44.858)mm.The median value of IPPL before surgery is 4.95(0,6.5)mm,of which 169 cases are less than 5mm and 169 cases are≥5mm.2.There are 321 patients in the CT group,71 cases(22.1%)are positive in basal margin and 87 cases(27.1%)are positive in apical margin,with an age of(69.935±7.073)years old.There are 99 cases of extraperitoneal approach via PORT,118 cases of modified extraperitoneal approach and 104 cases of transperitoneal approach.Preoperative median PSA is 14.34(9.02,18.205)ng/ml,of which 96,161 and 64 cases are PSA<10,10-20 and>20ng/ml respectively.The median prostate volume is 43.68(29.41,62.555)ml,of which 81,118 and122 cases are<30,30-50 and>50ml respectively.The preoperative ISUP grade1,2,3,4 and 5 have 52,56,92,61 and 60 cases respectively.Clinical T stage T1-2 stage has 223 cases,T3-4 stage has 98 cases.Median PSAD is0.33(0.18,0.605)ng/ml~2.The median value of IPPL before operation is4.9(2.7,10)mm,of which 167 cases are less than 5mm and 154 cases are≥5mm.3.Univariate analysis in MRI group shows that preoperative ISUP grade(P<0.001),clinical T stage(P<0.001),preoperative PSA(P<0.001),circumference of bladder neck(P=0.041),prostate volume(P=0.036),IPPL(P<0.001)and PSAD(P=0.003)are associated with basal positive surgical margin.Preoperative ISUP grade,clinical T stage,preoperative PSA,circumference of bladder neck,prostate volume,IPPL and PSAD are included in multivariate logistic regression analysis.The result shows that preoperative PSA,clinical T stage,IPPL and preoperative ISUP grade are independent risk factors for basal positive surgical margin.4.Univariate analysis in MRI group shows that age(P=0.044),preoperative ISUP grade(P<0.001),clinical T stage(P<0.001),preoperative PSA(P<0.001),IPPL(P=0.049)and PSAD(P<0.001)are associated with apical positive surgical margin.Age,surgical approach,preoperative ISUP grade,clinical T stage,preoperative PSA,IPPL and PSAD are included in multivariate logistic regression analysis.The result shows that preoperative PSA,clinical T stage,surgical approach and preoperative ISUP grade are independent risk factors for apical positive surgical margin.5.Univariate analysis in CT group shows that preoperative ISUP grade(P<0.001),clinical T stage(P<0.001),IPPL(P<0.001),preoperative PSA(P<0.001)and PSAD(P=0.003)are associated with postoperative basal positive surgical margin.Peoperative ISUP grade,clinical T stage,IPPL,preoperative PSA and PSAD are included in multivariate logistic regression analysis.The result shows that peoperative ISUP grade,clinical T stage,IPPL and preoperative PSA are the independent risk factors for basal positive surgical margin.6.Univariate analysis in CT group shows that preoperative ISUP grade(P=0.004),clinical T stage(P=0.002),IPPL(P=0.02),preoperative PSA(P=0.002)and PSAD(P=0.041)are associated with apical positive surgical margin.Preoperative ISUP grade,clinical T stage,IPPL,PSAD,preoperative PSA,surgical approach and age are included in multivariate logistic regression analysis.The result shows that preoperative ISUP grade,clinical T stage,surgical approach and preoperative PSA are independent risk factors for apical positive surgical margin.7.The AUC of positive prediction model of basal positive surgical margin based on MRI is 0.818(0.759,0.877),and the sensitivity and specificity are respectively 0.838 and 0.722.The AUC of positive prediction model of apical positive surgical margin based on MRI is 0.771(0.718,0.823),and the sensitivity and specificity are respectively 0.744 and 0.673.The AUC of positive prediction model of basal positive surgical margin based on CT is 0.777(0.718,0.836),and the sensitivity and specificity are respectively 0.69 and 0.74.The AUC of positive prediction model of apical positive surgical margin based on CT is0.71(0.65,0.77),and the sensitivity and specificity are respectively 0.609 and0.705.8.The results of Hosmer-Lemeshow goodness of fit test shows that theχ~2value of the positive prediction model of basal positive surgical margin based on MRI is 9.025,P=0.34.Theχ~2value of the positive prediction model of apical positive surgical margin based on MRI is 4.495,P=0.81.Theχ~2value of the positive prediction model of basal positive surgical margin based on CT is 4.538,P=0.806.Theχ~2value of the positive prediction model of apical positive surgical margin based on CT is 3.325,P=0.912.The P values of Hosmer-Lemeshow goodness-of-fit test of the above four models are all>0.05.It is suggested that there is no significant difference between the predicted value of the model and the actual observed value,and the prediction models have good calibration ability.Conclusion:Logistic multivariate regression analysis shows that preoperative PSA,clinical T stage,IPPLand preoperative ISUP grade are independent risk factors for basal positive surgical margin,while preoperative PSA,clinical T stage,surgical approach,and preoperative ISUP grade are independent risk factors for apical positive surgical margin in MRI group.In CT group,preoperative PSA,clinical T stage,IPPL and preoperative ISUP grade are independent risk factors for basal positive surgical margin,while preoperative PSA,clinical T stage,surgical approach,and preoperative ISUP grade are independent risk factors for apical positive surgical margin.In both MRI group and CT group,the risk of basal positive surgical margin after RARP increases in patients with IPPL≥5mm compared with<5mm.The four positive surgical margin predictive models all have good discrimination and calibration.According to the alignment diagram,the incidence of basal and apical positive surgical margin after RARP can be easily predicted,which has certain clinical value,but it still needs further verification and improvement.