Purpose: The aim of the current study was to determine in retrospect how many of a group of patients who underwent radical prostatectomy were correctly classified with an insignificant prostate carcinoma by means of preoperative diagnostics. Furthermore, we are aiming at finding preoperative parameters which predict an insignificant prostate carcinoma with higher accuracy. The current inclusion parameters of AS will be verified with regard to their reliability, and we will discuss the possibility of improving their prediction accuracy.
Methods: We examined the data of 308 consecutive patients who were diagnosed with a clinically insignificant prostate carcinoma and therefore would be suited for AS, but opted for a radical prostatectomy. According to the literature(1), the following inclusion criteria were chosen for our evaluation: a proven prostate carcinoma, detected by either ultrasonically guided transrectal core needle biopsy (cT1c) with at least six obtained samples and with a maximum of two positive samples on one side and a less than a 50 % tumor rate per sample, or a 5 % or lower tumor rate found in the tissue obtained by transurethral prostate resection (cT1a). The PSA value in all cases was below 10 ng/ml and the Gleason Score ≤6. The probability of a preoperative "undergrading" or "understaging" was determined as a function of preoperative parameters like Gleason Score, PSA value, the number of collected samples and positive samples obtained by core needle biopsy, prostate volume, and PSA density. Based on the available preoperative data, we developed and tested several regression models for the identification of independent factors for upgrading and upstaging.
Results: Within the examined patient population, 232 of 308 patients (75 %) were, according to their final prostate histology, diagnosed with a stage ≥pT2b prostate carcinoma. Eight percentage of the patients who had undergone surgery had a stage ≥pT3a carcinoma, and 118 of 308 (38 %) had a Gleason Score of 6 or higher. Positive lymph nodes and an infiltration of the seminal vesicle each occurred in 1 % of the cases. Histopathologic positive margins of resection existed in 33 of 308 patients (11 %). Independent factors for upgrading and upstaging a prostate volume of <50 ml and a preoperative Gleason Score of ≤6 were identified.
Conclusion: The presented results show that the current inclusion criteria for AS are insufficient. For many patients, the beginning of the necessary therapy is delayed. According to our data, the prostate volume, the preoperative Gleason Score, and the number of positive samples obtained by transrectal core needle biopsy have the highest predictive power with regard to aggressiveness and expansion of the tumor. Despite the consideration of all these preoperative parameters, the differentiation of the prostate carcinomas was underrated in a third of all cases. The expansion of the tumor within the prostate was underrated even in three fourths of the cases.