The impact of the inclusion of endorectal coil magnetic resonance imaging in a multivariate analysis to predict clinically unsuspected extraprostatic cancer

Abstract

The introduction of the endorectal coil magnetic resonance imaging (MRI) technique has improved the accuracy of preoperative staging for prostate cancer. This study quantifies the improvement in the ability to identify clinically unsuspected extraprostatic disease with the use of the endorectal coil MRI. A retrospective review of the pathologic findings of 347 patients with prostate cancer treated with a radical retropubic prostatectomy was performed. The preoperative clinical indicators including prostate specific antigen (PSA), clinical stage, Gleason score, and endorectal coil MRI data were employed in a multivariate analysis to identify patients who were at high risk for seminal vesicle invasion (SVI) or extracapsular extension (ECE). The sensitivity, specificity, and positive and negative predictive values for predicting SVI and ECE were calculated using the significant clinical indicators found on the multivariate analysis. The clinical factors identified on multivariate analysis as significant predictors of SVI include the endorectal coil MRI data (P < 0.0001), PSA (P = 0.0096), and the Gleason score (P = 0.012). Endorectal coil MRI data (P < 0.0001), PSA (P = .0001), and Gleason score (P < .0001) were significant predictors of ECE. In the patient subgroup with PSA (> 10-20 ng/ml) and Gleason score of 5 to 7, the addition of the endorectal coil MRI data enabled an additional 71 and 27% of patients with SVI and ECE, respectively, to be correctly identified. These patients would have been missed based on the prediction obtained from the PSA and Gleason score alone. The use of the endorectal coil magnetic resonance imaging data, in addition to prostate specific antigen and Gleason score, provides a more accurate prediction of the pathologic outcome of seminal vesicle invasion and extracapsular extension than the PSA and Gleason score alone for the patient subgroup with a PSA of greater than 10 to 20 ng/ml and Gleason score of 5 to 7.