MRI Accuracy for Prostate Cancer Challenged

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Clinically significant tumors outside of index lesions often missed, study finds.
Clinically significant tumors outside of index lesions often missed, study finds.

BOSTON—Multiparametric magnetic resonance imaging (mpMRI) frequently misses clinically significant prostate tumors outside index lesions, according to study findings presented at the American Urological Association's 2017 annual meeting.

In a study that included 244 PCa patients who underwent mpMRI with subsequent biopsy, Armando Stabile, MD, of Vita-Salute San Raffaele University in Milan, Italy, and colleagues found that mpMRI missed clinically significant PCa (Gleason sum of 7 or higher) outside of index lesions in 34% of cases.

When investigators stratified patients according to targeted biopsy results, the detection rate of clinically significant PCa outside the index lesion was 10% and 30% of men with negative and positive targeted biopsy findings, respectively. On multivariate analysis, PSA level, prostate volume, positive digital rectal examination, and previous negative biopsy independently predicted the overall presence of clinically significant PCa outside the index lesion. PI-RADS, index lesion volume, and number of index lesions detected on mpMRI were not associated with overall detection of clinically significant PCa outside the index lesion.

Despite the presence of clinical predictors, neither patient characteristics nor mpMRI data can reliably select patients who would be candidates for targeted biopsy alone. The investigators concluded that, based on their data, systematic biopsies always should be performed in conjunction with targeted biopsy in men with suspected clinically significant PCa  at mpMRI.

The men had a median PSA level of 7 ng/mL and median prostate volume of 47 cc. Their median number of random cores and index lesions was 12 and 1, respectively. The median index lesion volume was 0.70 cc.

References

Stabile A, Dell'Oglio P, Gandaglia G, et al. Multiparametric MRI cannot predict clinically significant prostate cancer outside the index lesion: Implications for extended biopsy templates. [abstract]. J Urol 2017:197(4S):e24. Presented as a poster at the American Urological Association 2017 annual meeting in Boston on May 12. Poster MP03-13.

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