The Effect of Prostate MRI on Cancer Staging and Radiotherapy Treatment Recommendations

Jonathan D. Tward, MD, PhD, Breanne E. Terakedis, MD, Marta E. Heilbrun, MD, William T. Lowrance, MD, MPH, Kristine Kokeny, MD, Dennis C. Shrieve, MD, PhD
Published: Monday, Apr 25, 2016
Jonathan D. Tward,
MD, PhD

About the lead author:

Jonathan D. Tward, MD, PhD
Huntsman Cancer Institute
the University of Utah
Salt Lake City, UT

Expert’s Perspective

Kevin Stephans, MD

Kevin Stephans, MD
Director of Genitourinary
Radiation Oncology
Cleveland Clinic

Abstract

Objective

To evaluate the role of magnetic resonance imaging (MRI) in the clinical staging of prostate cancer in the definitive and salvage settings, and to identify changes in treatment recommendations.

Materials and Methods

Between November 2008 and November 2011, 114 patients referred for radiotherapy (RT) consultation underwent a prostate-protocol MRI of the prostate and pelvis. Charts were retrospectively reviewed for demographic and clinical information.

Results and Conclusions

Eighty-six patients were evaluated for definitive treatment, 26 for salvage treatment, and 2 for RT planning in the adjuvant setting. Of the definitive subjects, MRI was performed after RT consultation in 68 patients and before consultation in 18 patients. For patients who underwent an MRI after consultation, MRI led to a change in treatment recommendation for 6 of 68 (9%) patients. Androgen deprivation therapy was added or extended in 3, prophylactic nodal RT was added to 3, and definitive nodal RT was added to 1.

Active surveillance was no longer recommended in two persons, and brachytherapy alone was no longer an option in two persons. Of the 86 definitive treatment patients, nodal metastases were identified in 6 (7%). For the 26 salvage patients, imaging did not lead to any changes in planned treatment. MRI evaluation can influence clinical decision making for both physician and patient, but how those decisions change outcome is still unresolved.

In most cases when treatment recommendations were modified based on MRI findings, therapy was escalated to correspond with clinical upstaging. It remains to be seen if this translates into improved disease control, and it is possible that the “Will Rogers phenomenon” (when moving an element from one set to another raises the average values of both) will result from incorporating the high-resolution MRI information into clinical decision making.

Introduction

Historically, magnetic resonance imaging (MRI) has not been routinely used for the diagnosis and staging of prostate cancer (PC). Accurate staging is important because there is wide variability in recommended treatment options and expected outcomes for patients with low-risk, intermediate-risk, and high-risk PC.1 Although useful for risk stratification, prostate-specific antigen (PSA) measurements can be unreliable correlates of tumor stage and disease burden.2 In addition, while digital rectal examination (DRE) can detect high-risk features such as extracapsular extension (ECE), DRE has been shown to have a low sensitivity.3,4 MRI has several possible roles in the management of PC, and its utility is being investigated in numerous single-institution studies. MRI findings have been correlated to pathologic features after radical prostatectomy.5-7 MRI is being evaluated as a tool for selecting patients who are appropriate active surveillance (AS) candidates, 8 despite some evidence that it may not be useful at predicting adverse pathologic features,9 or for predicting risk of recurrence based on high-risk features.10-14

A better understanding of tumor extent and location within the gland may lead to improvements in therapeutic decision making and in surgical and radiotherapy (RT) treatment planning. Use of prostate MRI could also lead to delivery of more aggressive therapies because of the detection of adverse features that would otherwise remain occult.

We reviewed the use of prostate MRI to characterize its effect on the clinical stage and subsequent treatment recommendations for patients referred for RT consultation.

Materials and Methods

After Institutional Review Board approval was obtained, all patients who were evaluated in the radiation oncology department and underwent a prostate protocol MRI between November 2008 and November 2011 were identified.


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