Quantification of tumor extension in prostate biopsies: importance in the identification of confined tumors

OBJECTIVE: To assess the importance of quantifying the adenocarcinoma in prostate biopsies when determining the tumor's final stage in patients who undergo radical prostatectomy. To identify the best methodology for obtaining such data. PATIENTS AND METHODS: Prostate biopsies from 132 patients were examined, with determination of Gleason histological grade and tumor volume in number of involved fragments, tumor extent of the fragment mostly affected by the tumor and the total percentage of tumor in the specimen. Theses parameters were statistically correlated with the neoplasia's final stage following the evaluation of radical prostatectomy specimens. RESULTS: An average of 12 and a median of 14 biopsy fragments were evaluated per patient. In the univariate analysis the Gleason histological grade, the largest tumor extent in one fragment and the total percentage of tumor in the specimen were correlated with tumor stage of the surgical specimen. In the multivariate analysis, the Gleason histological grade and the total percentage of tumor were strongly correlated with the neoplasia's final stage. The risk of the tumor not being confined was 3 for Gleason 7 tumors and 10.6 for Gleason 8 tumors or above. In cases where the tumor involved more than 60% of the specimen, the risk of non-confined disease was 4.4 times. Among 19 patients with unfavorable histological parameters, Gleason > 7 and extension greater than 60% the tumor final stage was pT3 in 95%. CONCLUSION: When associated to the Gleason histological grade, tumor quantification in prostate biopsies is an important factor for determining organ-confined disease, and among the methods, total percentage of tumor is the most informative one. Such data should be included in the pathological report and must be incorporated in future nomograms.