Preoperative nomograms incorporating magnetic resonance imaging and spectroscopy for prediction of insignificant prostate cancer

Abstract

Objectives • To validate previously published nomograms for predicting insignificant prostate cancer (PCa) that incorporate clinical data, percentage of biopsy cores positive (%BC+) and magnetic resonance imaging (MRI) or MRI/MR spectroscopic imaging (MRSI) results. • We also designed new nomogram models incorporating magnetic resonance results and clinical data without detailed biopsy data. • Nomograms for predicting insignificant PCa can help physicians counsel patients with clinically low-risk disease who are choosing between active surveillance and definitive therapy. Patients and methods • In total, 181 low-risk PCa patients (clinical stage T1c–T2a, prostate-specific antigen level < 10 ng/mL, biopsy Gleason score of 6) had MRI/MRSI before surgery. • For MRI and MRI/MRSI, the probability of insignificant PCa was recorded prospectively and independently by two radiologists on a scale from 0 (definitely insignificant) to 3 (definitely significant PCa). • Insignificant PCa was defined on surgical pathology. • There were four models incorporating MRI or MRI/MRSI and clinical data with and without %BC+ that were compared with a base clinical model without %BC and a more comprehensive clinical model with %BC+. • Prediction accuracy was assessed using areas under receiver–operator characteristic curves. Results • At pathology, 27% of patients had insignificant PCa, and the Gleason score was upgraded in 56.4% of patients. • For both readers, all magnetic resonance models performed significantly better than the base clinical model (P ≤ 0.05 for all) and similarly to the more comprehensive clinical model. Conclusions • Existing models incorporating magnetic resonance data, clinical data and %BC+ for predicting the probability of insignificant PCa were validated. • All MR-inclusive models performed significantly better than the base clinical model.

Performance Characteristics of MR Imaging in the Evaluation of Clinically Low-Risk Prostate Cancer: A Prospective Study

“…Thus, it appears that MR spectroscopic imaging alone is not sufficient to reliably detect prostate cancer in low-risk patients. However, as noted earlier, when combined MR imaging and MR spectroscopic imaging data were interpreted at the per-patient level, nomograms incorporating the MR imaging and MR spectroscopic imaging data with clinical variables were shown to help predict clinically insignificant cancer better than the basic clinical nomogram (15,30).…”

Prostate Cancer: Can Multiparametric MR Imaging Help Identify Patients Who Are Candidates for Active Surveillance?

“…In addition, the patient had to have had undergone a preoperative multiparametric MR imaging examination (with at least three of four of the following available sequences: triplane T2-weighted MR imaging, diffusion-weighted [DW] MR imaging, MR spectroscopy, and dynamic contrast material-enhanced MR imaging) at 3.0 T, followed by promising results have been published by several groups, the accurate characterization of disease extent remains a source of concern when committing a patient to AS. Moreover, the situation is confounded by a considerable rate of misclassification and inconsistency when current risk assessment schemes are utilized (12)(13)(14)(15)(16). A major concern is that results of random 12-core biopsies do not accurately reflect the aggressiveness of the disease.…”

“…However, this study did not include multiparametric MR imaging. Recently, Shukla-Dave et al (16) reported results of a newly designed nomogram that incorporates T2-weighted MR imaging and MR spectroscopy findings in 181 patients and concluded that the model nomogram improved the predictive accuracy for clinically unimportant prostate cancer, with areas under the curve that increased from 0.56 to 0.77 (P , .001). Although the exact multiparametric MR imaging techniques and analytic methods used in our study are different from these published results, our findings also support the incorporation of multiparametric MR imaging findings into clinical-pathologic nomograms.…”

Active Surveillance of Prostate Cancer: Use, Outcomes, Imaging, and Diagnostic Tools

“…A follow-up study of 181 patients revealed an AUC of only 0.738 for low-risk disease (defined as ≤pT2, Gleason grade<4, and tumor volume ≤ 0.5 cc) for those who underwent radical prostatectomy. 61 The National Cancer Institute nomogram, which uses only mpMRI criteria, generated an AUC of 0.71 for predicting candidates for AS in a cohort of 85 patients, 60 of whom had very low-risk disease (≤cT1c, PSA density <0.15, biopsy Gleason score ≤6, ≤ 2 positive biopsy cores, and ≤50% cancer involvement in any biopsy core). 62 This nomogram was developed with biopsy pathology as an endpoint, which is a method that has not been validated.…”