Study of diagnostic accuracy of Fagan's two-step nomogram in increasing the value of predictive tools for prostate cancer: application of specific spatial distribution of positive/negative bioptic cores to predict extracapsular extension

摘要

BackgroundProstate cancer (PC) represents the second most frequent cancer in the male population worldwide. It is mandatory to have a very accurate staging to choice the best possible treatment.AimsTo test the possibility of improving the performance of Partin's tables in predicting the pathological staging of PC by introducing bioptic parameters through an innovative statistic tool (Fagan's two-step nomogram).MethodsWe prospectivelly collected data of all 1048 consecutive patients undergoing saturation 24-core transrectal prostate biopsy. Then, in eligible 94 patients, we compared the prediction of presence/absence of extracapsular extension of neoplasm (EPE+/-), with pathological assessment of invasion through (pseudo)capsule in the prostatectomy specimens. Starting from the probability of EPE- (pre-test probability, calculated with formula 100%-risk of EPE+), we used Fagan's nomogram to examine the diagnostic sensitivity (DSe) and specificity (DSp) of negative lateral bioptic cores.ResultsWe specifically analyzed the status of lateral cores in each side (94 patientsx2 sides=188 sides). Lateral cores were negative in 42.5% of sides (80/188) with a DSe and DSp of 91.7 and 45.4%, respectively. In these sides, the mean probability of EPE+ according to Partin's tables was 21.6%. With Fagan's nomogram, the post-test probability of EPE+ when all lateral cores were negative was 14.1%, with a substantial gain of 7.5%.DiscussionThe spatial distribution of bioptic positive cores allowed us to demonstrate the role Fagan's nomogram in increasing the accuracy of already existing, predictive tools for PC.ConclusionsThis pioneering study may justify the use of the above nomogram in testing local predictive parameters in combination with pre-existing nomograms.