Multiparametric magnetic resonance imaging localizes established extracapsular extension of prostate cancer, "Beyond the Abstract," by Tom S. Feng, MD

BERKELEY, CA (UroToday.com) - Accurate clinical staging is important for managing prostate cancer. Compared with organ-confined disease, prostate cancer with extracapsular extension is associated with decreased overall and cancer-specific survival following radical prostatectomy. Moreover, even the extent of extracapsular extension predicts disease recurrence and survival. Traditional methods for clinically staging prostate cancer, including the digital rectal examination and transrectal ultrasound, yield low accuracy for identifying extracapsular extension. Multiparametric MRI, however, may be a better tool for preoperative staging because it has the potential to directly visualize the prostate cancer and its relationship to the prostate capsule. Its functional sequences, such as diffusion-weighted imaging and dynamic contrast enhancement, in conjunction with traditional T2-weighted imaging, have led to increased sensitivity and specificity of MRI for prostate cancer detection.

In our study, we investigated whether multiparametric MRI can localize extracapsular extension of prostate cancer. In addition, we determined if MRI can accurately identify established versus focal extension in each zone of the prostate. For this study, the prostate was divided in 6 zones, which were labeled left vs right and apex vs mid vs base. We identified 112 patients who underwent multiparametric MRI and radical prostatectomy at our institution. Images were reviewed by a genitourinary radiologist with expertise in prostate MRI. The pathology was reviewed by a genitourinary pathologist.

MRI accurately detected extracapsular extension in all zones of the prostate gland, but detection rates were lowest at the apex. Furthermore, while MRI was able to predict established extracapsular extension, it was not accurate in detecting focal extracapsular extension, defined as 5 or fewer glands outside the prostate. We found the overall sensitivity, specificity, positive predictive value, and negative predictive value for multiparametric MRI in detection of extracapsular extension to be 70.7%, 90.6%, 57.1%, and 95.1%, respectively.

In summary, our study confirmed the usefulness of multiparametric MRI for predicting extracapsular extension. This study demonstrates that MRI can accurately predict established but not focal extension in each zone of the prostate. Despite such promising results, not every patient may need a pre-operative MRI and the cost of obtaining a MRI on every patient prior to prostatectomy may be prohibitively high. Therefore, in a separate study, our group is assessing how clinical nomograms can be used to identify patient subsets most likely to benefit from a MRI.

Written by:
Tom S. Feng, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

Division of Urology, Cedars-Sinai Medical Center, Los Angeles, CA USA

Multiparametric magnetic resonance imaging localizes established extracapsular extension of prostate cancer - Abstract

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