Date of Award

January 2016

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Preston Sprenkle

Second Advisor

Toby Chai

Abstract

A particularly challenging subpopulation of prostate cancer patients are those who present with a persistently elevated PSA and suspicion of prostate cancer despite having had one or more prior negative prostate biopsies. These patients may benefit from the improvements made in prostate imaging through multiparametric MRI (mpMRI) and MRI-guided prostate biopsy techniques. In this study, we evaluate mpMRI and MRI-US fusion biopsy as a means of detecting clinically significant cancer as well as a potential indicator for avoiding repeat biopsies. We performed a retrospective study of 374 men seen between 12/2012 and 06/2015. All patients underwent pre-biopsy mpMRI to identify regions of interest (ROIs) within the prostate and each was assigned an MRI suspicion score. All patients then underwent a 12-core standard trans-rectal mapping biopsy, and all patients with ROIs identified on mpMRI underwent MRI-US fusion targeted biopsy. We defined cancer as any Gleason score ≥ 6, and we defined clinically significant cancer as Gleason score ≥ 3+4. Statistical analysis was performed using chi squared, Fisher’s exact, student’s t- test, one-way ANOVA, and multivariate logistic regression. All test results were considered statistically significant if p < 0.05. 143 patients were included in our analysis. Overall cancer detection rate was 42.66%, and the clinically significant cancer detection rate was 27.27%. For standard 12-core mapping biopsy, the cancer detection rate was 34.97%, and the clinically significant cancer detection rate was 18.18%. For men who underwent targeted biopsies, the cancer detection rate of the targeted biopsies was 40.5%, and the clinically significant cancer detection rate was 27.27%. In total, 21.50% of patients were upgraded by inclusion of targeted biopsy. For the 72 patients with no cancer on targeted biopsy, only 2 were found to have clinically significant cancer on mapping biopsy. A total of 213 ROIs were identified following mpMRI. Cancer was found in 32.86% of the ROIs and clinically significant cancer was found in 22.54%. For the 22 patients with no target identified on MRI, none were found to have clinically significant cancer. Age, PSA, MRI suspicion score, and PSA density were correlated with clinically significant. Anterior location of ROI was significantly correlated with presence of cancer and higher grade cancer, particularly on targeted biopsy. For clinically significant cancer detected on targeted biopsy, multivariate logistic regression revealed that the only significant independent predictor of disease was the presence of an anteriorly located ROI on mpMRI (OR 4.50, p < 0.01). In men with one or more previous negative biopsies and continued suspicion for prostate cancer, mpMRI and MRI-US fusion targeted biopsy provide greater detection rate of clinically significant disease compared to standard 12-core TRUS biopsy. Men with negative MRI findings may be able to avoid or delay biopsy. Patients with high MRI suspicion score lesions and those with anterior lesions are at increased risk for significant disease and should be treated with the necessary diligence.

Comments

This is an Open Access Thesis.

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